Senior Research Engineer - Learning to Rank

🏢 Summary: Senior Research Engineer role focused on designing, evaluating, and deploying production-grade machine learning models for search, ranking, and ads at scale. The position combines applied ML research with end-to-end ownership of solutions, from data exploration to production deployment. It involves translating state-of-the-art research into business impact while mentoring others and collaborating on large-scale systems. 🗂️ Requirements: Master’s or PhD in Machine Learning, Computer Science, Mathematics, Statistics or related STEM field, Strong knowledge of deep learning techniques, Experience in at least one domain: Information Retrieval or Natural Language Processing, Ability to conduct scientific research and iterative experimentation, Experience working with complex, real-world datasets, Proficiency in Python for ML development, Experience with ML frameworks such as PyTorch or TensorFlow 📃 Skills: Python, PyTorch, TensorFlow, Transformers, Pandas, NumPy, DeepLearning, NeuralNetworks, ContrastiveLearning, SemiSupervisedLearning, InformationRetrieval, NLP, Kubernetes, Docker, GitHub, GitHubActions, GCP, AWS, Azure, LLMs 🏢 Description: In the Learning to Rank team we develop machine learning models for search, ranking and ads. Our models serve millions of searches a day. We develop and apply state-of-the-art machine learning methods, helping Allegro grow and innovate with artificial intelligence. Beyond bringing AI to production, we are committed to advance the understanding of machine learning through open collaboration with the scientific community. About the role: As a Senior Research Engineer, you will work at the intersection of cutting-edge machine learning research and real-world products used at scale. You’ll take ownership of ML solutions end to end - from exploring complex data and selecting the right methods, to rigorous evaluation and production deployment. This role is for someone who enjoys navigating uncertainty, keeping pace with a fast-moving ML landscape, and turning research insights into tangible business impact, while also shaping ML expertise within the team and beyond. In your daily work you will handle the following tasks End-to-end ML ownership: Design and deliver production-ready machine learning solutions for Allegro products Data exploration: Analyze and understand complex data sets, identifying relevant data sources for ML use cases Model development & evaluation: Train, evaluate, and experiment with applied ML models using reliable evaluation methods Applied ML research: Translate state-of-the-art ML research into practical improvements for real-world solutions Tooling & methodology: Select ML tools and techniques that best fit concrete business needs Production collaboration: Work closely with cross-functional teams to deploy ML solutions into production Knowledge sharing: Spread ML expertise through internal sessions, presentations, and research activities Mentorship & expertise: Support junior team members and act as a trusted ML expert within the organization We are looking for people who Have a master's or PhD in machine learning, mathematics, computer science, statistics or other STEM fields Have a good knowledge of deep learning techniques (neural networks, contrastive learning, semi-supervised learning) in at least one domain (information retrieval, natural language generation or understanding, etc.) Know the methodology of conducting scientific research and the use of iterative processes of conducting experiments Have experience in working with real data that deviate from the standard, well-developed collections used in research Know Python and libraries necessary to work with model development (PyTorch, Tensorflow, Transformers, Pandas, Numpy, etc.) Nice-to-have: Understanding of Information Retrieval (IR) area Published research papers in ML-related topics Experience in business cooperation, deployments of ML-based solutions in commercial environments Prior experience in running large-scale computation on cloud platform (GCP, AWS or Azure) Prior experience in using LLMs for synthetic data generation/solving business problems What's in it for you Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. Long term discretionary incentive plan based on Allegro.eu shares (restricted stock units). Annual bonus based on your annual performance and company results. Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: Technical Team Leader role in the Recommendation team, combining hands-on development (20–50%) with leading a team delivering scalable, high-performance recommendation systems. The position focuses on designing and implementing distributed systems while ensuring engineering best practices and close collaboration with data and business teams. You will drive technical quality, architecture, and reliable delivery in a high-traffic environment. 🗂️ Requirements: Experience leading a development team as Tech Lead or Team Leader, Strong experience with Java, Kotlin or Scala, Active hands-on coding experience, Strong knowledge of testing, CI/CD and scalable architecture, Experience with high-traffic distributed systems, Experience in data engineering, Ability to ensure code quality through code reviews and TDD, Proficiency in English (B2+) 📃 Skills: Scala, Java, Kotlin, Python, SpringBoot, ApachePekko, ApacheSpark, GCP, Kubernetes, Docker, Consul, GitHub, GitHubActions, CICD, TDD, Microservices 🏢 Description: About the role Join the Recommendation team! You will have a chance to build tools for recommendations on Allegro - one of the most visible products on the platform. Your team work closely with the Machine Learning team, creating the best experience for customers. High performance, engineering best practices and great atmosphere in the team guaranteed! We are looking for a leader who is still close to technology. In this role, you will spend around 20-50% of your time on technical work (coding, code reviews, architecture), with the remaining time focused on team development and business collaboration. Important things for you Contract of employment, tax-deductible costs Depending on your annual assessment and the company's results we offer: Annual bonus based on your annual performance and company results. Long term discretionary incentive plan based on Allegro.eu shares (restricted stock units). Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. Our team is based in Warsaw. What will you do? Lead the development team (5-7 members) – ensuring accurate, scalable, and reliable delivery predictions Technical leadership – mentoring, code reviews, ensuring high code quality Design and implementation of key systems (languages: Scala, Java/Kotlin, Python, stacks: Spring Boot, Apache Pekko, Apache Spark, Google Cloud Platform) Collaboration with cross-functional teams - data science, data engineering, analytics, UX, operations Ensuring high quality - clean code, code review, TDD, CI/CD to ensure the quality and maintainability Who are we looking for? Experience in leading a team (Java/Kotlin and/or Scala) as a Tech Lead or Team Leader Still actively coding and eager to maintain technical expertise Strong knowledge of engineering best practices (testing, CI/CD, scalable architecture) Experience with high-traffic distributed systems and data engineering Ability to bridge technical and business perspectives Proficiency in English (B2+) Nice to have Experience with ML Familiarity with GCP data engineering tools: BigQuery, Cloud Composer, Dataproc What's in it for you: Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: Engineering role focused on designing, building, and optimizing AI-driven microservices that power a conversational marketplace assistant. The position involves LLM orchestration, Retrieval-Augmented Generation, semantic search, and high-performance retrieval in a cloud-native environment. You will own end-to-end development of AI services across Java/Kotlin and Python ecosystems, ensuring scalability, low latency, and high availability. 🗂️ Requirements: Proficiency in Python, Proficiency in Java, Proficiency in Kotlin, Experience with LLM orchestration, Experience with Retrieval-Augmented Generation (RAG), Experience with semantic search and vector search, Experience building microservices, Experience with cloud-native architectures, Ability to design and optimize high-availability systems, English level B2 or higher 📃 Skills: Python, Java, Kotlin, Spring, ADK, LangChain, Langfuse, LLM, RAG, LoRA, PEFT, AutoGen, CrewAI, Kubernetes, Docker, Consul, GitHub, GitHubActions, VectorSearch, Embeddings 🏢 Description: About the job: Performance & Scale: Design, build, and optimize AI-driven systems that process complex natural language interactions. Delivering low-latency, high-quality responses from our AI Assistant requires high-availability and smart optimization of LLM and retrieval workloads in practice. Modern Tech Stack: Work with a world-class, cloud-native polyglot environment. Our core backend technologies include Java , Kotlin , Spring, and ADK . At the same time, our AI and orchestration layer heavily relies on Python . You will utilize Python and LangChain for complex LLM orchestration, alongside Langfuse for observability, prompt tracking, and evaluation. We leverage advanced vector search and modern ML solutions to make our assistant truly smart. True Ownership & Autonomy: We live by a "you build it, you run it" philosophy. You'll join an agile, autonomous team with full ownership of your AI microservices and data pipelines, from design to deployment; and improvements are dictated by results of our own experiments and AI evaluation metrics. Complex Challenges: From LLM orchestration and Retrieval-Augmented Generation (RAG) to semantic search optimization, you'll tackle the complex backend problems that power a conversational marketplace assistant. You will work across the Java/Kotlin and Python ecosystems, integrating advanced embedding models, prompt pipelines, and vector databases to ensure our AI deeply understands and accurately retrieves information. In our domain, we focus on delivering the core search and retrieval capabilities for the Allegro AI Assistant. We maintain a critical entry point for users looking to discover products, compare offers, and get personalized recommendations through natural conversations. Striving for relevancy and accuracy first, we are designing, implementing, and operating an extensive system combining modern microservice architecture with Large Language Models, high-performance retrievers, and vast data sources. We care about data quality, robust context building, and near real-time accuracy to best guide users through a highly dynamic marketplace via an intelligent, conversational interface. Important things for you: Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. The salary range for this position depending on the skill set is as follows (contract of employment, tax-deductible cost): PLN 14 200 - 20 200 Annual bonus based on your annual performance and company results. Our team is based in Poznań. We are looking for people who: Code in Python, Java and Kotlin ; Expect work that requires creative approach to search experience challenges, to be proud of enjoying its results together with all Allegro users; Want to create solid code, eagerly accept comments and share knowledge during code reviews; Can look for effective solutions to the requirements set by users; Want to constantly develop and update their knowledge; Know English at at least B2 level. Nice to have: You are open to diverse technologies and workflows, including dev-operational tools on one hand, and working with data on the other. Basic experience with LLM tuning (LoRA, PEFT), training and evaluation pipelines for models and/or basic frameworks for building AI Agents (Agent Development Kit, LangChain, AutoGen, CrewAI) would be great! What's in it for you: Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: The role focuses on designing, building, and optimizing AI-driven backend systems that power a large-scale conversational assistant with low-latency, high-availability requirements. You will work across Java/Kotlin and Python ecosystems to implement LLM orchestration, RAG pipelines, and semantic search solutions within a cloud-native microservices architecture. The position involves full ownership of AI microservices and data pipelines from design to deployment in a production-scale environment. 🗂️ Requirements: Proficiency in Python, Proficiency in Java, Proficiency in Kotlin, Experience with LLM orchestration and RAG, Experience with microservices architecture, Experience with vector search and semantic search, Experience with cloud-native environments, Ability to design and optimize high-availability, low-latency systems, English level B2 or higher 📃 Skills: Python, Java, Kotlin, Spring, ADK, LangChain, Langfuse, LLM, RAG, Kubernetes, Docker, Consul, GitHub, GitHubActions, VectorSearch, Microservices 🏢 Description: About the job: Performance & Scale: Design, build, and optimize AI-driven systems that process complex natural language interactions. Delivering low-latency, high-quality responses from our AI Assistant requires high-availability and smart optimization of LLM and retrieval workloads in practice. Modern Tech Stack: Work with a world-class, cloud-native polyglot environment. Our core backend technologies include Java , Kotlin , Spring, and ADK . At the same time, our AI and orchestration layer heavily relies on Python . You will utilize Python and LangChain for complex LLM orchestration, alongside Langfuse for observability, prompt tracking, and evaluation. We leverage advanced vector search and modern ML solutions to make our assistant truly smart. True Ownership & Autonomy: We live by a "you build it, you run it" philosophy. You'll join an agile, autonomous team with full ownership of your AI microservices and data pipelines, from design to deployment; and improvements are dictated by results of our own experiments and AI evaluation metrics. Complex Challenges: From LLM orchestration and Retrieval-Augmented Generation (RAG) to semantic search optimization, you'll tackle the complex backend problems that power a conversational marketplace assistant. You will work across the Java/Kotlin and Python ecosystems, integrating advanced embedding models, prompt pipelines, and vector databases to ensure our AI deeply understands and accurately retrieves information. In our domain, we focus on delivering the core search and retrieval capabilities for the Allegro AI Assistant. We maintain a critical entry point for users looking to discover products, compare offers, and get personalized recommendations through natural conversations. Striving for relevancy and accuracy first, we are designing, implementing, and operating an extensive system combining modern microservice architecture with Large Language Models, high-performance retrievers, and vast data sources. We care about data quality, robust context building, and near real-time accuracy to best guide users through a highly dynamic marketplace via an intelligent, conversational interface. Important things for you: Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. The salary range for this position depending on the skill set is as follows (contract of employment, tax-deductible cost): PLN 14 600 - 20 825 Annual bonus based on your annual performance and company results. Our team is based in Poznań. We are looking for people who: Code in Python, Java and Kotlin ; Expect work that requires creative approach to search experience challenges, to be proud of enjoying its results together with all Allegro users; Want to create solid code, eagerly accept comments and share knowledge during code reviews; Can look for effective solutions to the requirements set by users; Want to constantly develop and update their knowledge; Know English at at least B2 level. Nice to have: You are open to diverse technologies and workflows, including dev-operational tools on one hand, and working with data on the other. Basic experience with LLM tuning (LoRA, PEFT), training and evaluation pipelines for models and/or basic frameworks for building AI Agents (Agent Development Kit, LangChain, AutoGen, CrewAI) would be great! What's in it for you: Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: The offer is for a Data Scientist responsible for designing, building, and deploying machine learning and AI solutions that drive marketplace performance at scale. The role covers end-to-end model development, from problem formulation to production, using advanced statistical methods, deep learning, and Generative AI on large-scale data in cloud environments. You will work closely with data engineers and business stakeholders to deliver impactful, production-grade ML systems. 🗂️ Requirements: Experience in data analysis using SQL, Experience building and deploying ML models in production environments, End-to-end experience designing machine learning models, Ability to translate business problems into ML solutions, Strong communication skills with business stakeholders, Experience with ML and AI, especially LLMs, Proficiency in Python, Understanding of statistical and machine learning methods, Practical and theoretical knowledge of Generative AI and Agentic AI, English and Polish proficiency at B2+ level, Degree in Mathematics, Physics, Economics, Computer Science or related field, or equivalent ML/Data Science experience 📃 Skills: Python, SQL, GCP, BigQuery, VertexAI, CloudComposer, Dataflow, Airflow, PySpark, LLM, GenAI, AgenticAI, DeepLearning, Bayesian, Boosting, CausalInference, Optimization, Kubernetes, Docker, Consul, GitHub, GitHubActions, Gemini, GPT 🏢 Description: Data Scientist Location: Warszawa, PL, 00-841 Company: Allegro sp. z o.o. Team: Technology Contract Type: Employee We are looking for a Data Scientist with a strong analytical mindset - someone who enjoys decoding market mechanisms and applying statistical models to solve complex platform puzzles. Our team drives the logic that powers a trustworthy and competitive marketplace. As part of the Tech organization dedicated to delivering the best experiences for our sellers, we specialize in data solutions focused on driving their growth - particularly through optimizing price competitiveness, expanding product selection, and supporting strategic campaigns. Composed of Data Scientists, Data Engineers, and Analysts, we develop statistical models and rules to measure and improve our products and services. We work in close collaboration with developers and product teams across the entire project lifecycle, from ideation to implementation. Our ultimate goal is to create a seamless experience where partners can rely on fair visibility rules, and Customers can trust every product detail they see on the platform. The brain of the entire Allegro. Here, we implement projects based on a practical application of artificial intelligence and Data Science on a scale unprecedented in Poland. In order to effectively implement ML solutions and automate existing processes, we need the support of inquisitive, experienced, and data-driven individuals. The ones willing to be up to date on newest algorithms and advancements in AI, from new deep learning architectures, explainable AI and GenAI but still grounded and aware of statistics and predictive modelling. In Allegro you will work with solutions from prototypes to create stable, high-performance solutions and combine these services with batch and stream processing analyzing real BigData (also in the public cloud). What will your job involve? Co-creating projects on each stage - from concept to productization - to deliver insights and models solving business problems from different areas Using a wide range of model types, including boosting models, Bayesian methods, causal inference, optimization methods, deep learning and Generative AI solutions including LLMs and Agentic AI Working hand-in-hand with our Data Engineers who support the heavy-lifting of data processing on GCP Working not only with tabular data, but also with spatial data, natural language texts, images and time series Taking part in implementations of off-line and on-line models Brainstorm, provide mentorship, share knowledge Cooperation with other teams: business stake-holders, analytics, data engineers Why should you work with us? Data Science plays a key role in the operation of Allegro - we are a data-driven technology company, and through the models and analyses provided you will have a significant impact on one of the largest eCommerce platforms in the world You will have a possibility of developing AI tools from prototypes to large production solutions that will have real impact on our users, merchants and employees. Thanks to the wide range of projects we carry out, you will never run out of interesting challenges Support of experienced Data Scientists - there is always someone to exchange ideas with, because we have the best specialists and experts in their field on board You will have access to huge data sets and the latest data processing technologies You will have the opportunity to learn the tools and technologies in practice: Python (including various ML libraries), GCP environment (BigQuery, VertexAI, Cloud Composer, Dataflow), Airflow, PySpark, Gemini/GPT models You will learn good programming, engineering and code management practices We share our knowledge at industry conferences and trainings, we are an active participant and co-creator of the Data Science / Machine Learning community in Poland and in the world Our offer is addressed to people who: Have experience in data analysis using SQL and building machine learning solutions in production environments, especially with end-to-end experience in designing ML models Want to translate business challenges into ML problems Can clearly communicate with business units - from formulating an analytical problem to a clear and intuitive presentation of results Have experience with ML and AI (especially LLMs) Are highly independent, showing strong work organization and taking full responsibility for their given projects Program in Python and efficiently use basic development tools Understand statistical and machine learning methods Embrace modern tooling, specifically possessing practical and theoretical knowledge of Generative AI and Agentic AI principles (coding tools, prompting, validation). The ideal candidate enthusiastically leverages GenAI coding tools (like Copilot) to boost and automate workflows,  remaining up-to-date and critically engaged with the newest GenAI tooling. Speak English and Polish at a B2+ level or higher Graduated with a degree strongly related to statistical/mathematical modeling, such as Mathematics, Physics, Economics, Computer Science (or similar major) or have job experience in data science / ML positions What's in it for you: Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. Annual bonus based on your annual performance and company results. Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale, which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: Senior Software Engineer role focused on building and scaling high-impact SEO and AI-driven products, including a Market Trend Prediction engine powered by LLMs. The position involves leading technical decisions, designing big data systems at massive scale, and driving projects from PoC to production in a cloud-based microservices environment. 🗂️ Requirements: Proficiency in Kotlin or Java, Experience with microservices architecture, Experience with GCP or Azure, Experience designing high-scale distributed systems, Experience with Big Data processing and analytics, Experience integrating LLMs or AI solutions into production systems, Fluent Polish (C1), English (B2 or higher) 📃 Skills: Kotlin, Java, Microservices, GCP, Azure, BigQuery, Airflow, Scala, Kubernetes, Docker, Consul, GitHub, GitHubActions, LLM, LangChain, AutoGen, LoRA, PEFT 🏢 Description: About the Team: SEOzord Team The SEOzord Team is the technical powerhouse behind Allegro’s SEO business unit. We are a specialized engineering squad (7 Developers, Product Manager and Leader) responsible for one of the largest traffic entry points on the Polish internet. We don't just maintain, we innovate. Last year, we launched Allegro Rankings, a product now scaling internationally. Currently, we are embarking on a high-impact mission: building a Market Trend Prediction engine using Large Language Models (LLMs). This is a rare opportunity to shape the architectural foundations of a project that turns AI experiments into production-grade business solutions Your main responsibilities: As a Senior Software Engineer, you will have the autonomy to drive technical decisions and lead the team through the complete lifecycle of complex products - from initial PoC to petabyte-scale production. Your main focus areas: Engineering Excellence: Leading by example through mentorship, high-quality code reviews, and establishing engineering standards. Big Data at Scale: Designing and optimizing systems that handle massive daily request volumes and extract actionable insights from vast datasets. AI Integration: Leading the technical integration of LLMs to drive our predictive capabilities. We are looking for people who: Tech Stack: You are proficient in Kotlin or Java and have a solid foundation in microservices and cloud environments (GCP/Azure). Ownership: You feel comfortable interacting with stakeholders and taking full end-to-end ownership—from requirements to post-deployment monitoring. Big Data Ambitions: You want to work with tools like BigQuery and Airflow. Experience with Scala is a significant plus. AI Curiosity (Nice to have): Familiarity with LLM tuning (LoRA, PEFT) or frameworks like LangChain/AutoGen will help you lead our newest initiatives. Language: You are fluent in Polish (C1) and English (min. B2) . Note: As our current workflow is linguistically homogeneous, Polish is a must-have for this role. What's in it for you: Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. The salary range for this position depending on the skill set is as follows (contract of employment, tax-deductible cost): 18 850 - 25 900 gross Annual bonus based on your annual performance and company results. Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: Senior Software Engineer role focused on building and scaling backend platform services that power web and mobile rendering infrastructure. The position involves architecting high-throughput microservices, maintaining platform stability, reducing technical debt, and supporting AI-driven developer tooling. The role offers hybrid work, performance bonuses, and opportunities to work with large-scale distributed systems. 🗂️ Requirements: Expertise in Kotlin, Expertise in Java, Experience with Spring, Experience with PostgreSQL, Experience with Couchbase, Experience with Kubernetes, Experience with Docker, Experience with microservice architectures, Ability to manage high-throughput systems, Backend engineering experience, System stability and SLA management, Mentoring and technical leadership skills 📃 Skills: Kotlin, Java, Spring, PostgreSQL, Couchbase, GCP, Hermes, Kafka, Kubernetes, Docker, TypeScript, React, GitHub, Consul, GitHubActions, LLM 🏢 Description: About the Job At Allegro, we operate at a massive scale where performance, reliability, and developer efficiency are paramount. Within the Frontend Platform area, we design and maintain the critical infrastructure and tools responsible for building and rendering every website and mobile screen across the entire ecosystem. Our internal, CMS-like solutions are utilized company-wide by everyone from engineers building individual components to non-technical content editors launching complex landing pages, campaign sites, and homepage partials. This high-throughput environment demands exceptional complexity management, structural scalability, and out-of-the-box architectural thinking to boost developer productivity and maintain our core services. The Role As a Senior Software Engineer, your primary focus will be the development, maintenance, and architectural evolution of our core frontend platform services. This is a highly impactful role where your work directly ensures the high availability and stability of Allegro's primary web and mobile rendering traffic. You will be at the very center of product delivery, helping the organization scale efficiently while keeping technical debt to a minimum. Key Responsibilities: Architect, develop, and scale core platform services and content management tools. The primary stack is backend-focused (Kotlin/Java, Spring, PostgreSQL, Couchbase, GCP, Hermes (our open source solution on top of Kafka), Kubernetes/Docker), with the opportunity to occasionally touch or collaborate on the frontend side (TypeScript/React). Actively monitor, optimize, and deep-dive into platform systems to ensure maximum stability, safeguard our SLAs, and reduce technical debt. Provide technical foundation and active support for critical business projects, ensuring new features can be deployed smoothly and swiftly. Lead software development initiatives, supervise and mentor other team members, and document software thoroughly. Analyze the needs of our internal users to deliver features that accelerate company-wide development and deliverability. Shape and develop the platform's foundation to support AI-driven tooling, ensuring our services are ready to seamlessly integrate with AI agents and next-generation developer assistants. Important things for you: Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. The salary range for this position depending on the skill set is as follows (contract of employment, tax-deductible cost): PLN 18 850 - 25 900 Annual bonus based on your annual performance and company results. Long term discretionary incentive plan based on Allegro.eu shares (restricted stock units). Our team is based in Poznań. We are looking for people who: Demonstrate deep expertise in backend engineering with Kotlin/Java. While the role is heavily backend-focused, any familiarity with frontend ecosystems is a great plus that will help you collaborate seamlessly across the platform. Are excited by the challenge of managing critical, high-throughput microservice architectures where system stability is a top priority. Enjoy working closely with an internal customer base, allowing you to receive rapid feedback on your work and see its immediate organizational impact. Are open to experimenting with cutting-edge efficiency boosters. Our team actively explores integrating AI Agents and LLMs into our internal tooling and workflows to optimize daily operations. What’s in it for you: Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: Backend engineering role in the Recommendation team focused on building and operating high-scale, high-availability microservices and ML-serving infrastructure in a cloud-native environment. The position involves designing distributed systems, data streaming solutions, and end-to-end ML systems that power real-time personalized recommendations. You will own services from design to deployment using modern technologies such as Kotlin, Spring, Kafka, Kubernetes, BigQuery, and Spark. 🗂️ Requirements: Proficiency in Kotlin or Java, Willingness to develop in Kotlin on greenfield projects, Experience with distributed systems and microservices architecture, Experience with cloud-native technologies and containerization, Ability to design high-availability and high-performance systems, Experience with data processing or data streaming systems, Understanding of ML model serving concepts, Experience with BigQuery or Apache Spark for data processing, English proficiency at B2 level or higher 📃 Skills: Kotlin, Java, Spring, Kafka, Kubernetes, Docker, Consul, GitHub, GitHubActions, BigQuery, Spark, Python, VectorSearch, Microservices, ML, Hermes 🏢 Description: About the job Massive Scale : Design, build, and optimize systems that handle thousands of requests per minute. This is high-availability, high-performance engineering in practice. Modern Tech Stack : Work with a world-class, cloud-native environment. Our core technologies include Kotlin, Spring, Kafka, and Kubernetes. We're not shy when it comes to ML too :) True Ownership & Autonomy : We live by a "you build it, you run it" philosophy. You'll join an agile, autonomous team with full ownership of your microservices, from design to deployment. Complex Challenges : From distributed systems and data streaming to algorithmic optimization, you'll tackle the complex backend problems that power a massive, real-time marketplace. End-to-End ML Systems: Bridge the gap between big data and real-time product impact. You’ll build the infrastructure for serving ML models , using BigQuery and Apache Spark for offline data processing and Vector Search databases for high-speed retrieval. You’ll integrate these components with our microservices architecture to create the sophisticated recommendation systems that power a personalized user experience. Join the Recommendation team! You will have a chance to build tools for recommendations on Allegro - one of the most visible products on the platform. Your team works closely with the Machine Learning team, creating the best experience for customers. High performance, engineering best practices and great atmosphere in the team guaranteed! Important things for you Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. The salary range for this position depending on the skill set is as follows (contract of employment, tax-deductible cost): PLN 11 200 - 15 250 Annual bonus based on your annual performance and company results. Our team is based in Warsaw. We are looking for people who Code in Kotlin or Java and are eager to master Kotlin by taking part greenfield project Want to be proud of the code they create ; they value high-quality code reviews and engage in substantive discussions on software engineering best practices; Are excited about building new products and want to experience the journey of launching a fresh project within the Allegro ecosystem; Are open to developing soft skills and exploring a full-stack mindset by learning new backend, frontend, and mobile technologies; Are open to incorporating AI coding assistants into their daily work to maximize efficiency and focus on complex problem-solving Can look for effective solutions to the requirements set by users; Want to constantly develop and update their knowledge; Know English at at least B2 level; Are eager to dive into the world of ML Engineering , learning how to serve ML models (using Python) and handle large-scale offline data processing using tools like BigQuery or Apache Spark. What's in it for you Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: Backend engineering role focused on building secure, scalable systems for fraud prevention, compliance, and data transparency in a large-scale marketplace environment. The position involves developing automation-driven backend platforms using Python, JVM technologies, cloud data tools, and modern infrastructure. The team offers high architectural autonomy, hybrid work, and opportunities to work with large-scale distributed systems and ML-supported solutions. 🗂️ Requirements: Python, Willingness to work with JVM languages, Experience with Kotlin, GCP, BigQuery, Dataproc, Clean code practices, Code reviews, Analytical mindset, Problem-solving skills, English B2 📃 Skills: Python, Kotlin, JVM, GCP, BigQuery, Dataproc, Spark, SQL, MachineLearning, MLOps, Kubernetes, Docker, Consul, GitHub, GitHubActions, MacBook, Windows 🏢 Description: About the job: Maintaining top-tier safety standards at macro scale: Allegro is a safe platform for millions of users. You will design, develop, and maintain backend systems that keep frauds and policy violations at an absolute minimum. Designing core data-sharing and transparency platforms: You will design, develop, and maintain high-security internal platforms responsible for trusted data exposure and compliance. Instead of dealing with legacy external tech, you will build modern abstraction layers that handle data flows, strict auditing, and access control. Data-driven engineering culture: We focus on automation, clean documentation, and code optimization. We actively eliminate repetitive manual work in favor of building stable, scalable system solutions. Mature and collaborative team: You will join a 6-person team with a strong senior presence. We heavily value engineering craftsmanship, knowledge sharing and high architectural autonomy. Technological Compliance & R&D: You will design solutions where advanced backend architecture meets evolving regulatory landscapes and market dynamics. Your work involves building intelligent tools that guarantee the transparency of our marketplace and quickly adapt to sophisticated, creative patterns, making our marketplace resilient to any emerging risks. Pragmatic Tech Stack : We select the best tools for the job rather than sticking to one framework. Our ecosystem includes JVM languages and Python. We process data using BigQuery and Spark jobs, utilize graph, relational and document databases, and implement traditional Machine Learning models to support decision-making. Driving Automation : You will play a key role in transforming how we handle verification processes. We are moving heavily towards automation to make our systems faster, more accurate, and less reliant on manual intervention. Important things for you: Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. The salary range for this position depending on the skill set is as follows (contract of employment, tax-deductible cost): PLN 18 850 - 25 900 Annual bonus based on your annual performance and company results. Long term discretionary incentive plan based on Allegro.eu shares (restricted stock units). Our team is based in Poznań. We are looking for people who: Code in Python and is willing to expand into JVM languages (Kotlin) to work with other parts of our system. Are comfortable with GCP tools , particularly BigQuery and Dataproc. Want to build solid, clean code , actively participate in code reviews, and enjoy sharing knowledge with the team. Have a strong sense of ownership and mission , wanting to directly impact the safety of millions of Allegro users. Possess an analytical mindset and a problem-solving attitude. Use AI tools to boost daily productivity but maintain critical thinking and never blindly accept code suggestions. Communicate in English at a B2 level or higher. Nice to have: Experience or strong interest in Machine Learning (ML) and MLOps What's in it for you: Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!

🏢 Summary: Backend Engineer role in the Advertising team focused on building and operating high-scale, cloud-native systems and end-to-end ML infrastructure for a real-time marketplace. The position involves developing microservices, data pipelines, and advertising systems using Kotlin/Scala, Spring, Kafka, and big data technologies. You will own services end-to-end in a high-availability environment handling massive traffic and complex distributed challenges. 🗂️ Requirements: Proficiency in Kotlin or Scala, Experience with Spring Boot, Experience with Kafka, Hands-on experience with Apache Airflow, Hands-on experience with Apache Spark, Proficiency in PostgreSQL, Experience with database migrations, Experience designing and integrating APIs, English level B2 or higher 📃 Skills: Kotlin, Scala, Spring, SpringBoot, Kafka, Airflow, Spark, PostgreSQL, BigQuery, Kubernetes, Docker, Consul, GitHub, GitHubActions, React, TypeScript 🏢 Description: About the job Massive Scale : Design, build, and optimize systems that handle thousands of requests per minute. This is high-availability, high-performance engineering in practice. Modern Tech Stack : Work with a world-class, cloud-native environment. Our core technologies include Kotlin, Spring, Kafka, and Kubernetes. We're not shy when it comes to ML too :) True Ownership & Autonomy : We live by a "you build it, you run it" philosophy. You'll join an agile, autonomous team with full ownership of your microservices, from design to deployment. Complex Challenges : From distributed systems and data streaming to algorithmic optimization, you'll tackle the complex backend problems that power a massive, real-time marketplace. End-to-End ML Systems: Bridge the gap between big data and real-time product impact. You’ll build the infrastructure using BigQuery and Apache Spark for offline data processing. You’ll integrate these components with our microservices architecture to create the sophisticated advertising system that powers a personalized user experience. Join the Advertising team! You will have a chance to build Allegro Ads - one of the most visible products on the platform. Your team works closely with the Machine Learning team, creating the best experience for customers. High performance, engineering best practices and great atmosphere in the team guaranteed! Important things for you Flexible working hours in the hybrid model (4/1) - working hours start between 7:00 a.m. and 10:00 a.m. We also have 30 days of occasional remote work. The salary range for this position depending on the skill set is as follows (contract of employment, tax-deductible cost): PLN 18 850 - 25 900 Annual bonus based on your annual performance and company results. Our team is based in Warsaw. We are looking for people who: Code in Kotlin or Scala and have experience with Spring Boot and Kafka to build robust backend systems; Have hands-on experience with Apache Airflow and Spark , enabling them to manage high-velocity data pipelines and build scalable reporting engines; Are proficient in PostgreSQL and have experience with database migrations and designing integrations via APIs; Enjoy close collaboration with Data Scientists and Analysts, working together to implement complex models and turn raw data into actionable insights; Are enthusiastic about AI and want to stay at the forefront of technical innovation; Want to build impactful tools for a diverse range of users, helping them understand campaign performance through advanced statistics and dashboards; Experience with frontend technologies (React/TypeScript) is a “Nice to have” to help build modern frontend reporting components; Are excited to join a growing team where they can influence the technical vision and help shape new projects from the ground up within the ecosystem; Know English at at least B2 level. What's in it for you: Well-located offices (with e.g. fully equipped kitchens, bicycle parking, terraces full of greenery) and excellent work tools (e.g., raised desks, ergonomic chairs, interactive conference rooms). A 16" or 14" MacBook Pro or corresponding Dell with Windows (if you don't like Macs) and all the necessary accessories. A wide selection of fringe benefits in a cafeteria plan - you choose what you like (e.g., medical, sports or lunch packages, insurance, purchase vouchers). English classes that we pay for related to the specific nature of your job. A training budget, inter-team tourism ( see more here ), hackathons, and an internal learning platform where you will find multiple trainings. An additional day off for volunteering, which you can use alone, with a team, or with a larger group of people connected by a common goal. Social events for Allegro people - Spin Kilometers, Family Day, Fat Thursday, Advent of Code, and many other occasions we enjoy. And that's just the beginning! You can read more about the benefits here . #goodtobehere means that: You will join a team you can count on - we work with top-class specialists who have knowledge- and experience-sharing in their DNA. You will love our level of autonomy in team organization, the space for continuous development, and the opportunity to try new things. You get to choose which technology solves the problem and you are responsible for what you create. You will value our Developer Experience and the full platform of tools and technologies that make creating software easier. We rely on an internal ecosystem based on self-service and widely used tools such as Kubernetes, Docker, Consul, GitHub, and GitHub Actions. Thanks to this, you can contribute to Allegro from your very first days on the job. You will be equipped with modern AI tools to automate repetitive tasks, allowing you to focus on developing new services and refining existing ones (also leveraging AI support). You will create solutions that will be used (and loved!) by your friends, family and millions of our customers. You will meet the Allegro Scale , which starts with over 1000 microservices, an open-source data bus (Hermes) with 300K+ rps, a Service Mesh with 1M+ rps, tens of petabytes of data, and production-used machine learning. You will become part of Allegro Tech - We speak at industry conferences, cooperate with tech communities, run our own blog (it's been over 10 years!), record podcasts, lead guilds, and we organize our own internal conference - the Allegro Tech Meeting. We create solutions we love (and can) to talk about! Send us your CV and… see you at Allegro!