Senior Full-Stack Software Engineer, Applied AI

🏢 Summary: Full-stack AI engineering role focused on building and scaling AI-powered features and infrastructure using Ruby on Rails and React. The position involves developing production-grade LLM applications, running experiments and A/B tests, and improving AI systems performance and reliability in a remote-first environment. 🗂️ Requirements: 6+ years of full-stack engineering experience on high-traffic production applications, Proficiency in Ruby on Rails, Experience with MySQL or PostgreSQL, Experience with ReactJS, Hands-on experience building AI features in production, Experience shipping RAG systems, AI agents, or LLM-powered tools, Ability to design and run A/B tests and AI evaluations, Experience optimizing performance, scalability, and database queries, Fluent English proficiency at CEFR C2 / ILR Level 5, Ability to work in a fast-paced, highly autonomous environment 📃 Skills: Ruby, Rails, MySQL, PostgreSQL, ReactJS, LLMs, RAG, AI, A/B, SQL 🏢 Description: About Us Circle is building an all-in-one platform for online communities, enabling creators, coaches, educators, and businesses to bring together their audience with discussions, live streams, events, chat, courses, and payments in one branded platform. The company operates as a fully remote team distributed across 30+ countries, collaborating asynchronously with a strong focus on documentation and high-impact work. Team members gather twice a year for global company offsites. About the role The Applied AI team is focused on leveraging AI and large language models to build innovative customer experiences. The role is for a full-stack engineer experienced in web frameworks, backend development, and infrastructure to develop AI-powered solutions across the platform. Projects include AI agents, Retrieval-Augmented Generation (RAG), AI evaluations and observability, and infrastructure for LLM inference. The role values hands-on experience building AI features and an experimentation mindset focused on rapid testing, A/B experiments, and iteration on production AI use cases. What you'll be doing - Ship full-stack AI projects end-to-end on a product built in Ruby on Rails backend and React frontend. - Design and run experiments, including A/B tests and AI evaluations, to validate AI features and measure impact. - Build and integrate AI infrastructure components optimized for performance and reliability. - Improve processes, tools, and systems to scale AI features into production-ready solutions. - Stay current with cutting-edge AI research, techniques, and tools. - Collaborate with leaders and designers throughout the feature design process. - Prioritize rapid iteration, experimentation, and learning while maintaining high code quality and user experience standards. What you'll need to be successful - 6+ years of experience as a full-stack engineer working on high-traffic production applications. - Experience handling scale-related challenges such as query optimization, migrations, and performance bottlenecks. - Strong proficiency in Ruby on Rails, MySQL or PostgreSQL, and ReactJS. - Hands-on experience building AI features in production, including RAG systems, AI agents, or LLM-powered tools. - Experience shipping real AI use cases beyond prototypes. - Strong experimentation mindset with experience designing and running A/B tests. - Ability to work effectively in a fast-paced environment with ambiguity. - Strong collaboration skills and accountability. - English proficiency at CEFR Level C2 / ILR Level 5. Compensation & Benefits - Salary range: $130,000 - $140,000 USD per year. - U.S.-benchmarked global compensation. - Equity with ongoing refresh grants. - 35 days of paid time off annually. - Remote-only work environment. - Twice-yearly company retreats in international locations. - Benefits package supporting health, wellbeing, and professional growth.

🏢 Summary: Opportunity to join an AI Ops team building and scaling AI-powered automation systems for global supply chain operations, partnering closely with engineering, product, and customers to drive adoption and deliver measurable value. The role focuses on deploying intelligent workflows, translating complex technical systems for users, and embedding with customer and operations teams to enhance execution. This is an onsite position in Chicago, San Francisco, or New York City. 🗂️ Requirements: College degree in analytics, finance, economics, STEM or related quantitative field, 1+ year experience in technology, data analysis or other technical quantitative field, Ability to understand complex technical systems and translate them for users, Experience working cross-functionally with engineering, product, or operations teams, Onsite availability 4+ days per week in Chicago, San Francisco, or New York City 📃 Skills: SQL, Python, Excel, Automation, Data, AI 🏢 Description: About the Role Loop is building an AI ops team that will own key automation and intelligence systems as Loop builds and scales them across its customer base. The team is disrupting traditional operations with AI-powered workflows that create 100X leverage for users, turning operators into analysts. Responsibilities include close partnership with engineering and product teams, internal roll-out of new systems and products, and driving adoption across the user base. This role requires a deep understanding of systems and their users (internal and external), the ability to translate complex technical work to everyday users, and strong problem-solving skills. This is an in-person role based in Chicago, San Francisco, or New York City, with the expectation of being onsite 4+ days per week. What You'll Do - Accelerate delivery of new product capabilities for global brands by understanding how customer outcomes are driven - Embed with customer, product, and operations teams to deliver increased customer value - Partner with AI engineers to deploy systems and products that automate workflows, reduce manual work, and improve user experience - Demonstrate strong execution skills and deep knowledge of the product offering and customer pain points - Build and maintain relationships with internal customer-facing stakeholders to ensure value delivery About You - College degree with a quantitative background in analytics, finance, economics, or similar STEM field - 1+ years of work experience in technology, data analysis, or other technical and quantitative fields - Ability to balance eagerness to learn with strong execution and problem-solving skills - Team-oriented mindset with interest in fast-paced, high-growth environments - Advanced Excel skills and SQL, Python, or other programming experience are a plus Compensation and Benefits The base pay range for this role is $80,000 to $125,000 annually, depending on experience, skills, qualifications, location, and business needs. In addition to base salary, the role may be eligible for equity. Benefits include health, dental, and vision insurance, 401(k) match, paid time off, paid holidays, and parental leave. Equal Opportunity The company is an equal opportunity employer committed to creating an inclusive environment for all employees. All qualified applicants will receive consideration without regard to legally protected characteristics.

🏢 Summary: Development role in an international team building a modern SaaS platform for the life science sector, focused on data management, process automation, and research tools. The position involves designing and developing a web application and APIs using Ruby on Rails, contributing to architecture decisions, and optimizing system performance and scalability. Work is carried out in an Agile environment with real impact on a global product. 🗂️ Requirements: Minimum 3 years of experience with Ruby on Rails, Experience building web applications, Experience with JavaScript, HTML, CSS, Experience designing and integrating APIs, Experience with AWS, Experience with CI/CD pipelines, Experience with Git version control, English proficiency at B2 level or higher, Availability for onsite onboarding (first 2 weeks) 📃 Skills: Ruby, Rails, JavaScript, HTML, CSS, API, AWS, CI/CD, Git, MySQL, Docker, ElasticSearch, Hotwire, React 🏢 Description: Dołącz do międzynarodowego zespołu pracującego nad nowoczesną platformą SaaS wykorzystywaną w obszarze life science. Projekt dotyczy rozwiązań wspierających zarządzanie danymi, automatyzację procesów oraz rozwój narzędzi badawczych wykorzystywanych przez organizacje na całym świecie. Lokalizacja biura: Wrocław. Model pracy: zdalnie w większości czasu pracy (praca z biura 1 raz na 2 tygodnie). Stack technologiczny projektu: Ruby on Rails, JavaScript, Hotwire / React, API, MySQL, AWS, Git, CI/CD, Docker, ElasticSearch . Zespół: liczy obecnie ok. 5 osób i działa w środowisku międzynarodowym. Zespół zlokalizowany jest częściowo w Polsce (Wrocław), Norwegii i Izraelu. Zakres obowiązków: Projektowanie i rozwój aplikacji webowej w Ruby on Rails Tworzenie i rozwój API platformy Implementacja nowych funkcjonalności oraz rozwój istniejących modułów Dbanie o jakość kodu (testy, utrzymanie, refaktoryzacja) Współpraca z zespołem produktowym oraz interesariuszami biznesowymi Udział w projektowaniu architektury i podejmowaniu decyzji technologicznych Optymalizacja wydajności oraz skalowalności systemu Wykorzystanie narzędzi AI wspierających proces developmentu (np. code review, generowanie kodu, testy) Praca w środowisku Agile w międzynarodowym zespole Główne wymagania: Minimum 3 lata doświadczenia w tworzeniu aplikacji webowych w Ruby on Rails Doświadczenie w pracy z JavaScript, HTML, CSS Znajomość pracy z API (projektowanie, integracje) Doświadczenie z AWS oraz CI/CD Doświadczenie z systemami kontroli wersji (Git) Znajomość języka angielskiego na poziomie min. B2 Umiejętność pracy w zespole oraz komunikacji w środowisku międzynarodowym Samodzielność, odpowiedzialność za realizowane zadania Gotowość do pracy stacjonarnej podczas onboardingu (2 pierwsze tygodnie pracy) Mile widziane: Doświadczenie z Hotwire lub React Doświadczenie z Docker, MySQL, ElasticSearch Doświadczenie w projektach SaaS Doświadczenie z narzędziami AI wspierającymi development Znajomość domeny life science Wyższe wykształcenie w obszaru nauk przyrodniczych Firma oferuje: Stałą, długofalową współpracę w oparciu o kontrakt B2B (+25 dni płatnego urlopu) Pracę zdalną w większości czasu pracy (praca z biura we Wrocławiu 1 raz na 2 tygodnie) Udział w rozwoju globalnego produktu technologicznego Pracę w międzynarodowym środowisku Realny wpływ na rozwój systemu oraz decyzje technologiczne Stabilny, długoterminowy projekt produktowy Kartę Multisport Pracę w zespole nastawionym na współpracę i dzielenie się wiedzą

🏢 Summary: Senior or Staff Backend Engineer role focused on architecting and scaling AI-native backend services for a modern accounting platform. The position involves designing distributed systems, building secure and high-performance APIs, and establishing engineering standards to support rapid, reliable product delivery. You will work closely with Product, AI, and Operations teams to build scalable data pipelines and incident response infrastructure. 🗂️ Requirements: 5–10+ years of backend engineering experience, Proven experience designing and operating production backend systems at scale, Strong expertise in API design and data modelling, Deep understanding of distributed systems and architectural trade-offs, Hands-on experience with AWS or GCP in production environments, Practical experience with CI/CD pipelines and automated testing, Experience building and maintaining observability and on-call practices 📃 Skills: TypeScript, Node.js, React, AWS, GCP, Terraform, PostgreSQL, OpenAI, Azure, CI/CD, APIs, DistributedSystems, DataModelling, Observability 🏢 Description: ABOUT THE COMPANY We're an applied AI company building an AI-native alternative to legacy accounting software — a market worth tens of billions in annual recurring revenue. Our mission is to help entrepreneurs focus on what matters in their business and life, and to help their accountants become more strategic. We've raised $20M from a group of top-tier investors and have grown ARR 60% month-on-month since our public launch. We now serve thousands of businesses and are expanding our product to serve accountants directly — creating a two-sided platform where both business owners and their accountants use and recommend us. We're at an early but proven stage, moving fast, and building a world-class engineering team in Wrocław to match our ambition. ABOUT THE ROLE We're looking for a Senior or Staff Backend Engineer to own and evolve our backend services as we scale. This is a broad, high-impact role — you'll architect new features, build the systems that underpin our core product, and set the engineering standards that shape how the whole team works. The focus is on building a modern, AI-native developer experience. That means working closely with Product, AI, and Operations teams to design agentic systems, distributed data pipelines, and scalable incident response infrastructure — and doing it in a way that lets the team ship with confidence multiple times a day. WHAT YOU'LL WORK ON Architecture and feature design Partner with Product, AI, and Operations teams to architect new features and complex agentic systems. Make clear architectural trade-offs that balance platform, product, and business goals. Backend services and APIs Build and maintain the backend services and APIs that power the core product. Ensure systems are secure, well-tested, and high performance. Distributed systems Design and implement distributed services to orchestrate data pipelines, automate investigations, and enable incident response at scale. Operational excellence Own operational best practices so the team can ship multiple times a day with confidence. Healthy on-call culture and strong observability are part of what you'll build and maintain. Engineering standards Set the bar for writing, communication, and system design across the team. Your influence will shape how a modern AI-native product is built. WHAT WE LOOK FOR 5–10+ years of backend engineering experience A strong track record designing, building, and operating production backend systems at scale. Deep backend fundamentals Expertise in API design, data modelling, and reasoning about distributed systems trade-offs. You understand the nuances, not just the patterns. AWS or GCP hands-on experience Solid understanding of how infrastructure decisions impact application reliability and performance. You've run things in production, not just designed them. CI/CD in practice Practical experience with testing and deployment strategies in high-frequency shipping environments. Observability and on-call maturity A solid grasp of what good observability looks like and how to build healthy on-call practices that don't burn people out. Bonus Experience at an early-stage or scaling startup. Exposure to modern AI and ML systems. Experience shipping product without a dedicated product manager. TECH STACK TypeScript, React, Node.js, AWS, Terraform, PostgreSQL, OpenAI, Azure AI. The team uses GitHub, Slack, Linear, Figma, and Notion day to day. THE TEAM Small, senior, and in-person. The office is in central Wrocław, next to the main train station. The expectation is 4–5 days a week in the office — this is a deliberate choice, not a compromise. Relocation support is available for the right candidate. COMPENSATION & BENEFITS Salary $130,000 – $190,000 USD depending on experience, plus competitive equity. Wellness and commute stipend $100 per month. Hardware Premium hardware provided — MacBook Pro and AirPods. Food Daily in-office lunch and dinner. Time off 20 PTO days plus 9 US public holidays. Relocation Support available for candidates relocating to Wrocław.

🏢 Summary: Full Stack Developer role focused on building and evolving a modern web application platform with complex workflows and data-driven features. The position involves developing and maintaining both frontend and backend components, ensuring scalability, performance, and reliability. You will collaborate within a cross-functional team to deliver iterative improvements using modern development practices and AI-assisted tools. 🗂️ Requirements: Experience in full stack web application development, Hands-on experience with React, Experience with C# and .NET or comparable backend technologies, Practical experience with SQL-based databases and writing queries, Experience using AI-assisted development tools (e.g., Claude, Cursor), Solid understanding of Git and version control workflows, Ability to work with and extend existing codebases 📃 Skills: React, TypeScript, C#, .NET, SQL, Git, REST, Claude, Cursor 🏢 Description: Project overview The project is a web based application platform designed to support complex user workflows and data driven features. It focuses on performance, maintainability, and iterative delivery of new capabilities. Team You will be part of a cross functional development team consisting of full stack developers, frontend specialists, backend engineers, and QA engineers. The team works collaboratively, reviews code regularly, and follows shared development standards and branching practices. Position overview We are looking for a Full Stack Developer to contribute to the development and evolution of a modern web application platform. You will work on both frontend and backend components, focusing on building reliable, scalable features and improving existing functionality. The role combines hands on development with close collaboration across engineering and product roles. Technology stack React, TypeScript, C#, .NET, SQL based databases, Git, REST APIs, AI assisted development tools such as Claude and Cursor Responsibilities Develop and maintain frontend features using React and related technologies Build and support backend services using C# and .NET Collaborate with team members on feature design, implementation, and code reviews Work with SQL based databases to design, query, and optimize data storage Use AI assisted development tools to improve development efficiency and code quality Follow established Git workflows and branching strategies Participate in troubleshooting, debugging, and performance improvements Requirements Experience building web application platforms in a full stack role Hands on experience with React for frontend development Experience with C# and .NET or comparable backend technologies Understanding of SQL based databases and practical experience writing queries Experience using AI tools to support software development, including Claude or Cursor Solid understanding of Git, version control, and common branching flows Ability to work with existing codebases and contribute to ongoing development Nice to have Experience with cloud based environments Familiarity with CI CD pipelines Experience working on large scale or long term web platforms Exposure to performance optimization and application monitoring What We Offer: Vacation days : Up to 26 business days per year. 10 illness/special days off per year (fully paid, no medical papers needed) for all contract types Health and life insurance (Luxmed) MyBenefit platform with Multisport option Internal psychological support service English language classes from the first working day Access to external learning platforms : O’Reilly, LinkedIn Learning, Udemy, and a wide catalog of diverse internal training Flexible workplace : work from the office, from home, or choose a hybrid option Tech Skills Mentoring Program Opportunities to develop as a public speaker, mentor, or technical interviewer Fully paid idle (bench) when not involved in a project Certification reimbursement (AWS, GCP, Microsoft, etc.)

🏢 Summary: Full-Stack Developer (Ruby on Rails) role within an R&D team building advanced life science research platforms. The position involves designing and delivering scalable, secure web solutions across frontend and backend, contributing to architecture and product direction. The engineer will work in an agile environment to enhance a multi-tenant SaaS platform used globally by researchers. 🗂️ Requirements: Minimum 3 years of professional web development experience, Strong hands-on experience with Ruby on Rails, Solid backend and frontend development knowledge, Experience with HTML, CSS, and JavaScript, Experience building and maintaining APIs, Experience with AWS and CI/CD pipelines, Proficiency with Git, Experience with AI-assisted development tools, Ability to develop scalable and secure applications 📃 Skills: Ruby, Rails, HTML, CSS, JavaScript, Hotwire, React, AWS, CI/CD, Git, Docker, MySQL, Elasticsearch, APIs 🏢 Description: For one of our clients, we are currently seeking an experienced Full‑Stack Developer (Ruby on Rails) to join an R&D team building advanced platforms for life science research. This role is ideal for an engineer who values clean architecture, high‑quality code, and modern web development practices. You will become part of an agile, highly motivated engineering team responsible for building and evolving a platform used daily by researchers and laboratories worldwide. As an experienced engineer, you will play a meaningful role in shaping the technical direction of the product and driving future platform improvements. Working closely with product leaders and management, you will ensure that our solutions continue to meet the needs of a growing scientific community. What You Will Do Design, implement, and ship new features as well as future releases of the platform across frontend and backend layers. Build, improve, and maintain robust platform APIs with a strong focus on scalability, reliability, and performance. Write clear, maintainable, and well‑tested code, following iterative and test‑driven development principles. Collaborate closely with product and management teams to transform business requirements into effective technical solutions. Help develop a highly scalable service deployed in multi‑tenant SaaS, single‑tenant SaaS, and on‑premise environments. Apply secure development practices and contribute to system scalability and performance optimization. Actively use AI‑assisted development tools to speed up coding, reviews, and testing workflows. Contribute positively to team collaboration, sharing ownership and fostering a supportive and enjoyable work culture. Experience & Technical Requirements Required: Minimum of 3 years of professional experience in web development, with solid knowledge of both backend and frontend development. Required: Strong, hands‑on experience with Ruby on Rails . Experience with several of the following technologies: HTML, CSS, JavaScript, Hotwire, React, AWS, CI/CD pipelines, Git . Experience with Docker is considered an advantage. Experience with MySQL is a plus. Experience with Elasticsearch is a plus. Hands‑on use of AI‑powered tools to accelerate development (e.g. AI‑assisted coding, automated code reviews, or testing). Experience integrating AI workflows into the software development lifecycle is considered a nice‑to‑have. Who You Are A collaborative team member who raises the technical bar and encourages excellence in others. Comfortable explaining ideas, designs, and decisions to both technical and non‑technical stakeholders. Able to thrive in a fast‑paced, agile environment where results are delivered in short cycles. Opinionated about technology choices and how to apply them effectively to deliver real value to users and the business. A pragmatic yet passionate polyglot programmer with a strong software engineering foundation. Open to experimenting with and adopting AI tools as part of everyday development work. Willing to work from the office at least two days per week, with flexibility to work remotely when needed. A background or degree in Life Sciences is a significant advantage. Hays Poland sp. z o.o. jest agencją zatrudnienia zarejestrowaną w rejestrze prowadzonym przez Marszałka Województwa Mazowieckiego pod numerem 361.

🏢 Summary: Full Stack Developer role focused on building and integrating LLM-powered features across React frontend and Python backend systems. The position involves working directly with APIs such as Claude and OpenAI to deliver AI-driven functionality while collaborating closely with product, QA, and engineering teams in EST overlap hours. Ideal for engineers with hands-on LLM integration and modern web development experience. 🗂️ Requirements: Commercial experience with LLMs (Claude, OpenAI APIs, similar, or custom integrations), Minimum 1 year of React experience (hooks, state management, component-driven development), Minimum 1 year of Python experience in API development and backend logic, Experience working in distributed teams with active collaboration, Upper-intermediate English level 📃 Skills: React, Python, LLM, Claude, OpenAI, API, FastAPI, AI, Prompting 🏢 Description: ID63542 AgileEngine is an Inc. 5000 company that creates award-winning software for Fortune 500 brands and trailblazing startups across 17+ industries. We rank among the leaders in areas like application development and AI/ML, and our people-first culture has earned us multiple Best Place to Work awards. Why join us If you're looking for a place to grow, make an impact, and work with people who care, we'd love to meet you! :) About the role We are looking for a Full Stack Developer to build and integrate LLM-powered features across frontend and backend systems. You will develop React components, extend Python backend services, and work directly with LLM APIs — including Claude, OpenAI, or similar — to deliver AI-driven product functionality. The role requires close collaboration with product, QA, and engineering teams with active overlap in EST hours. What you will do Develop and integrate LLM-based functionality, including prompt engineering, API-based model usage, and AI workflows; Build and maintain React-based frontend components; Develop and extend Python backend services, including APIs, integrations, and data processing; Collaborate closely with product, QA, and engineering teams in overlapping EST hours; Participate in design discussions and contribute to scalable, maintainable solutions. Must haves Commercial experience with LLMs, preferably Claude , OpenAI APIs , similar APIs, or custom model integration; 1+ year of React experience with hooks, state management, and component-driven development; 1+ year of Python experience in API development and backend logic; Experience working in distributed teams with active collaboration; Upper-intermediate English level. Nice to haves Experience with FastAPI or similar frameworks; Exposure to AI evaluation, prompt testing, or AI quality considerations; Prior work on data-heavy or AI-driven products. The benefits of joining us Professional growth: Accelerate your professional journey with mentorship, TechTalks, and personalized growth roadmaps Competitive compensation: We match your ever-growing skills, talent, and contributions with competitive USD-based compensation and budgets for education, fitness, and team activities A selection of exciting projects: Join projects with modern solutions development and top-tier clients that include Fortune 500 enterprises and leading product brands Flextime: Tailor your schedule for an optimal work-life balance, by having the options of working from home and going to the office – whatever makes you the happiest and most productive. Meet Our Recruitment Process Asynchronous stage – An automated, self-paced track that helps us move faster and give you quicker feedback: Short online form to confirm basic requirements 30–60 minute skills assessment via Codility – a platform founded in Poland that helps us provide quicker feedback and streamline this stage of the process. 5-minute introduction video Synchronous stage – Live interviews Technical interview with our engineering team (scheduled at your convenience) Final interview with your future teammates If it’s a match — you’ll get an offer!

🏢 Summary: Mid Full Stack Engineer role focused on building and improving AI-powered enterprise products across frontend and backend systems. The position involves developing web applications, APIs, and production features using modern technologies while collaborating closely with cross-functional teams. Candidates will work with AI development tools and contribute to scalable, high-quality software in a fast-growing environment. 🗂️ Requirements: 2–5 years of experience building production web applications, Knowledge of React, Knowledge of TypeScript or another modern frontend framework, Experience building backend services, Experience building REST APIs, Familiarity with testing and version control, Understanding of web application architecture, Understanding of client-server communication, Problem-solving skills, Attention to code quality, Strong communication skills, Experience using AI development tools, Willingness to collaborate across engineering, product, and design teams 📃 Skills: React, TypeScript, REST, Git, GitHub, Copilot, Claude, ChatGPT, Python, Node.js, AWS, GCP, Azure, Docker, CI/CD 🏢 Description: About Us Many companies want to use AI agents, but these agents often struggle with complex business tasks. We solve this problem by building a platform that understands company knowledge, policies, processes, and workflows, enabling AI to make reliable decisions instead of simply generating answers. Our technology helps businesses automate up to 85% of customer cases, reduce handling time by 20–25%, and complete tasks that previously took hours in just a few seconds. Our mission is simple: to give people better answers everywhere. About the Role We are looking for a Mid Full Stack Engineer who enjoys building products and solving real user problems. In this role, you'll work across both the frontend and backend, collaborating closely with engineers, product managers, and designers to deliver new features and improve existing ones. You'll have the opportunity to work with modern AI technologies, contribute to production systems, and grow your technical skills in a fast-moving environment. If you enjoy learning, shipping high-quality software, and working on products used by enterprise customers, we'd love to hear from you. Responsibilities - Build and maintain product features across both frontend and backend. - Develop user interfaces using modern frontend technologies. - Build and extend backend APIs and business logic. - Collaborate with engineers, product managers, and designers to implement new functionality. - Improve application performance, reliability, and usability. - Write clean, maintainable, and well-tested code. - Participate in code reviews and engineering discussions. - Help monitor production systems and improve features based on user feedback and product data. - Use AI development tools to improve productivity and software development workflows. Requirements - 2–5 years of experience building production web applications. - Good knowledge of React, TypeScript, or another modern frontend framework. - Experience building backend services and REST APIs. - Familiarity with modern software engineering practices, testing, and version control. - Understanding of web application architecture and client-server communication. - Good problem-solving skills and attention to code quality. - Strong communication skills and willingness to collaborate across engineering, product, and design teams. - Experience using AI tools such as GitHub Copilot, Claude Code, ChatGPT, or similar in day-to-day development. - Curiosity, ownership of your work, and a desire to continuously learn. Nice to Have - Experience with Python, Node.js, or both. - Experience working on AI-powered products or LLM integrations. - Familiarity with cloud platforms (AWS, GCP, or Azure). - Knowledge of Docker, CI/CD, or modern deployment workflows. - Understanding of performance optimization and accessibility best practices. What We Offer - B2B contract. - Company stock options. - MacBook Pro for work. - Modern technology stack with opportunities to contribute to open-source projects. - Access to advanced AI development tools, including GitHub Copilot, Claude Code, OpenAI Codex, TypingMind, and MCP Servers. - The opportunity to work on real AI products used by enterprise customers. - A collaborative engineering culture focused on learning, ownership, and continuous improvement. - The chance to grow your career alongside experienced engineers in a fast-growing AI company. Why Join Us Our leadership team brings deep experience in AI and knowledge management. We've raised over $60 million in funding and achieved three consecutive years of 3× growth. We believe great products are built by great teams, and our culture is shaped by these values: - Quality - We care about craftsmanship and building software that lasts. - Momentum - We move quickly, iterate often, and continuously improve. - Accountability - We take responsibility for our work, communicate openly, and support one another. - Hard Work - We believe ambitious goals require dedication and teamwork. - Learning Agility - We stay curious, embrace feedback, and continuously develop our skills. - Adapt and Thrive - We welcome change and see challenges as opportunities to improve. - Win Together - We succeed by collaborating, sharing knowledge, and helping each other grow.

🏢 Summary: Backend Engineer role focused on building and maintaining high-volume, complex API integrations using pure Ruby in a transactional, money-flow–critical domain. The position involves designing robust backend services, ensuring reliability and transactional integrity, and collaborating with stakeholders and external partners. The environment emphasizes AWS-based infrastructure, DevOps practices, and secure, scalable solutions. 🗂️ Requirements: Strong experience with Ruby (beyond Ruby on Rails), Proven experience delivering backend services in complex domains, Expertise in API design and third-party integrations, Familiarity with transactional systems and reliability constraints, Solid understanding of DevOps practices, Experience with Infrastructure-as-Code, Hands-on experience with AWS (EC2, S3, RDS), Experience with Docker, Experience with Redis, Strong analytical skills, Clear stakeholder communication skills 📃 Skills: Ruby, Redis, Docker, AWS, EC2, S3, RDS, Infrastructure-as-Code, API, Thin, EventMachine, Sinatra, Elasticsearch 🏢 Description: Project overview This project focuses on building and maintaining high-volume, complex API integrations with external partners in a domain where transactional integrity and money flows are critical. Position overview We are looking for a Backend Engineer with strong expertise in pure Ruby. In this role, you will design and maintain robust backend services and high-volume API integrations in a domain where transactional integrity and money flows are critical. You’ll collaborate closely with stakeholders and external partners to deliver secure, scalable solutions. Technology stack Ruby (pure Ruby, not Rails-centric) Redis Docker AWS services (EC2, S3, RDS) Infrastructure-as-Code tools Responsibilities Design and implement robust backend services using Ruby Develop and maintain complex API integrations with external systems Ensure transactional integrity and reliability in high-volume environments Collaborate with stakeholders and external partners to clarify requirements Contribute to infrastructure automation and deployment processes Participate in technical design discussions and solution shaping Requirements Strong experience with Ruby (beyond Ruby on Rails) Proven track record of delivering backend services in complex domains Expertise in API design, integration, and third-party connectivity Familiarity with transactional systems and reliability constraints Solid understanding of DevOps practices and Infrastructure-as-Code Hands-on experience with AWS services (EC2, S3, RDS) Knowledge of Docker for containerization Experience with Redis Strong analytical skills for navigating intricate business rules Clear and confident communication skills for stakeholder engagement Nice to have Thin, EventMachine, Sinatra Exposure to Elasticsearch. Experience in financial or transactional domains. What We Offer: Vacation days : Up to 26 business days per year. 10 illness/special days off per year (fully paid, no medical papers needed) for all contract types Health and life insurance (Luxmed) MyBenefit platform with Multisport option Internal psychological support service English language classes from the first working day Access to external learning platforms : O’Reilly, LinkedIn Learning, Udemy, and a wide catalog of diverse internal training Flexible workplace : work from the office, from home, or choose a hybrid option Tech Skills Mentoring Program Opportunities to develop as a public speaker, mentor, or technical interviewer Fully paid idle (bench) when not involved in a project Certification reimbursement (AWS, GCP, Microsoft, etc.)

🏢 Summary: Full Stack Developer (Ruby on Rails) role in an R&D team building a scalable SaaS platform for laboratory data management and AI-powered research tools. The position focuses on developing and maintaining full-stack features with strong emphasis on performance, scalability, and code quality. You will work on multi-tenant and on-premise deployments in a collaborative, agile environment. 🗂️ Requirements: 3+ years frontend development experience in large-scale web applications, Strong proficiency in React, Strong proficiency in JavaScript, Strong proficiency in HTML, Strong proficiency in CSS, Practical experience with Ruby on Rails and ability to work with existing codebases, Degree in Computer Science or equivalent experience 📃 Skills: React, JavaScript, HTML, CSS, Ruby, Rails, TDD, APIs, SaaS, AWS, Docker, MySQL, ElasticSearch, Redux, Lit, CICD, AI 🏢 Description: 📍 Location: Wrocław, Poland (Hybrid) 📅 Employment Type: Full-time, B2B (up to 18.000PLN net monthly)/CoE (up to 14.000PLN gross monthly) 🏢 We are hiring for our client (life sciences / SaaS R&D domain) About the Project We are currently looking for an experienced Full Stack Developer (Ruby on Rails) on behalf of our client — an innovative company operating in the life sciences sector. You will join an R&D team working on a cutting-edge platform used by scientists and research organizations worldwide. The platform focuses on laboratory data management, workflow automation, and AI-powered tools that support research and production processes. Responsibilities Design and implement new features across the full stack Develop and maintain platform APIs with a strong focus on scalability, reliability, and performance Write clean, well-tested, and maintainable code following TDD and iterative practices Collaborate closely with product and business teams to translate requirements into technical solutions Contribute to building scalable solutions deployed as: multi-tenant SaaS single-tenant SaaS on-premise systems Ensure application security, performance optimization, and system scalability Leverage AI-assisted tools to accelerate development, testing, and code quality Actively contribute to team collaboration and a positive engineering culture Requirements ✅ Must-have At least 3 years of frontend development experience in large-scale web applications Strong proficiency with: React JavaScript HTML / CSS Practical familiarity with Ruby on Rails (ability to read and contribute to existing codebases) Degree in Computer Science or equivalent experience ✅ Nice to have Experience with: Redux Toolkit / Lit AWS / CI/CD pipelines Docker MySQL ElasticSearch Experience using AI tools in development (e.g., coding assistants, automated testing, code review) Exposure to integrating AI workflows into the SDLC Candidate Profile Strong team player with excellent communication skills (technical and non-technical) Comfortable working in a fast-paced, agile environment Opinionated about code quality and technology usage, while remaining pragmatic Passionate about building meaningful products Open to adopting AI tools as part of daily development workflows Hays Poland sp. z o.o. jest agencją zatrudnienia zarejestrowaną w rejestrze prowadzonym przez Marszałka Województwa Mazowieckiego pod numerem 361.