Senior Full Stack Engineer

🏢 Summary: Senior Software Engineer role focused on designing and delivering new features and PoCs end-to-end on a large-scale SaaS and data platform. The position emphasizes backend development in Python, extending a mature system, and leveraging AI/LLM tools to accelerate development and improve engineering workflows. Fully remote with high ownership and impact on product direction. 🗂️ Requirements: 7+ years of Software Engineering experience, Strong experience with Python, Experience with Django, Experience building large-scale production systems, Experience designing and maintaining REST APIs, Strong understanding of distributed systems, Strong understanding of backend architecture, Daily practical use of AI tools and LLMs in development workflows, Experience with cloud environments, Ability to independently design and deliver end-to-end solutions, Professional English proficiency 📃 Skills: Python, Django, REST, API, SaaS, LLM, AI, Cloud, DistributedSystems, Backend 🏢 Description: Does building awesome, innovative products that add up to something meaningful sound like a dream come true? Come join us and make that vision a reality! About We are looking for a product-driven Senior Software Engineer who thrives in fast-paced environments and enjoys turning ideas into practical, user-focused solutions. In this role, you will independently design and deliver new features and PoC end-to-end on top of an existing large-scale SaaS and data platform. Rather than working in a purely greenfield environment, you will extend and evolve a mature platform with new capabilities, focusing on speed, usability, and real customer value. A key part of this role is the daily use of AI and LLM-based tools to accelerate development workflows, prototyping, research, testing, and delivery. We are looking for someone who not only uses AI tools effectively but also understands how to integrate AI reasoning and automation into modern software engineering practices. Responsibilities Independently design, prototype, and deliver new features and PoCs end-to-end Translate product ideas into scalable and user-focused backend solutions Validate technical feasibility and make pragmatic architectural decisions Use AI tools, coding copilots, and LLM-based workflows to accelerate development, experimentation, and delivery Build and maintain scalable backend services and REST APIs using Python (preferably Django) Collaborate closely with Product, Design, and Engineering teams to shape and refine new features Contribute to engineering quality through code reviews, technical guidance, and knowledge sharing Continuously explore and introduce practical AI-driven workflows that improve engineering productivity and delivery speed Our offer Competitive salary on B2B contract Fully remote position Real impact and independence at work Individual career path Work-life balance A non-corporate atmosphere where innovation, personal growth, and teamwork thrive 100+ smart, curious & ambitious engineers What you bring 7+ years of experience as a Software Engineer Strong experience with Python and preferably Django Experience building and maintaining large-scale production systems and REST APIs Strong understanding of distributed systems and modern backend architecture Demonstrated daily use of AI tools and LLMs in real engineering workflows (e.g. code generation, prototyping, refactoring, testing, documentation, automation) Experience integrating with complex platforms and cloud environments Ability to independently deliver solutions with minimal supervision Strong product mindset and focus on solving real user problems Excellent communication and collaboration skills across Product, Design, and Engineering teams Curiosity, ownership, and passion for learning and experimenting with new technologies Professional level of English Nice to Have Experience mentoring or coaching engineers Experience working with data products and related scalability challenges Experience promoting AI-driven engineering practices and helping teams adopt modern AI workflows Benefits International Projects Small Teams Flat Structure Friendly Atmosphere Flexible Hours Individual Career Path We want your TALENT! Don’t hesitate and APPLY! We are happy to tell you more details about this position in a phone call. Our recruitment process is very fast and straightforward to ensure a great experience from the first interview to joining your dream team!

🏢 Summary: Senior Full-stack Engineer role focused on building and scaling a modern B2B SaaS platform for subscription-based e-commerce. The position involves end-to-end feature delivery, architectural decisions, and improving system scalability and reliability. High-impact role with strong ownership over technical direction and product evolution. 🗂️ Requirements: 7+ years engineering experience in complex systems, Strong system design skills, Experience designing scalable architectures, Full-stack development experience, Experience building SaaS platforms, Experience with e-commerce systems 📃 Skills: JavaScript, TypeScript, SaaS, Architecture, Scalability, Reliability, APIs, Ecommerce, Payments, Cloud 🏢 Description: Senior Full-stack Engineer Our client is building a modern B2B SaaS platform that enables businesses to launch and scale subscription-based models for physical and digital products. The product sits at the intersection of e-commerce, payments, and developer tooling, with a strong focus on extensibility and developer experience. The team is lean, senior, and highly experienced, backed by strong investors and industry advisors. They operate with high autonomy, fast execution, and strong ownership culture. Role We are looking for a Senior Full-stack Engineer to help shape the next evolution of the platform. You will work across architecture, product, and infrastructure, focusing on scalability, reliability, and developer experience. This is a high-impact role where you will influence both technical direction and product decisions. Responsibilities Build and evolve a scalable SaaS platform Design and deliver new features end-to-end Improve performance, reliability, and system architecture Collaborate with product, design, and growth teams Requirements 7+ years of engineering experience in complex systems Strong architectural and system design skills Ability to choose appropriate technologies per problem Experience working in cross-functional teams Strong communication in Polish and English Startup mindset: ownership, speed, adaptability Experience with e-commerce platforms is a plus Offer High-impact role in a senior engineering team with real product ownership and influence. Competitive salary plus ESOP, fully remote work (Poland), regular team offsites, and modern tooling including MacBook Pro and AI credits. Direct access to founders, investors, and advisors.

🏢 Summary: Senior backend‑heavy fullstack engineer to build a greenfield prenatal screening diagnostics product, owning features end‑to‑end across backend and frontend. The role focuses on Java/Spring Boot architecture, data modeling, APIs, and AWS infrastructure, with React/TypeScript contributions as needed. AI coding tools are expected as a core part of daily development in a regulated, production environment. 🗂️ Requirements: Strong Java and Spring Boot expertise, Experience designing APIs and domain models, Solid understanding of OOP and SOLID principles, Ability to define service boundaries and system architecture, Working proficiency in React and TypeScript, Proven experience using AI coding tools in daily development, Experience writing unit, integration, and API tests, Experience with PostgreSQL schema design and query optimization, Experience deploying and operating workloads on AWS, Ability to work in greenfield, ambiguous environments 📃 Skills: Java, Spring, SpringBoot, React, TypeScript, PostgreSQL, AWS, ECS, EKS, RDS, Lambda, S3, OOP, SOLID, REST, AI, Claude, Cursor, Testing 🏢 Description: Our client — a global leader in healthcare and diagnostics — is building a new prenatal screening diagnostics product from the ground up. We are looking for a senior backend‑heavy fullstack engineer who can own features end‑to‑end — from data modeling and APIs to the UI. The role offers real ownership within a highly regulated, impact‑driven product environment. Using AI tooling as a core part of daily engineering work is expected — not as an experiment, but as a standard way of building and delivering software. What You'll do: Own features end-to-end: design, implement, test, deploy, and maintain across the full stack. Work split ~80% backend, 20% frontend. Make foundational architectural decisions on a greenfield codebase — data models, API contracts, service boundaries, test strategy Build and maintain the Java/Spring Boot backend that powers the product's core logic Contribute to the React/TypeScript frontend when needed — you're backend-primary, but you ship UI when the team needs it Integrate AI coding tools into your daily workflow to accelerate delivery while maintaining code quality — and help the team adopt these practices Collaborate directly with product stakeholders to refine requirements in a fast-moving, low-ceremony environment Requirements: Strong Java and Spring Boot expertise — clean API design, domain modeling, sound architectural trade-offs. You think in terms of service boundaries, data flow, and maintainability, not just making it work Solid grasp of software design principles — object-oriented programming, SOLID, clean architecture, separation of concerns. You write code that the next person can read, extend, and trust. You know when a pattern helps and when it's ceremony Working proficiency in React and TypeScript — you can pick up frontend tasks, build components, and integrate with backend APIs independently Proven experience integrating AI coding tools (Claude Code, Cursor, or equivalent) into daily development workflow — including prompt design for code generation, output validation, and actively preventing AI-generated technical debt. You can describe concrete examples of where AI accelerated your delivery and where you chose to override it Testing as a professional discipline, not a checkbox — you write unit, integration, and API tests as part of delivery, own the test pyramid decisions, and treat untested code as unfinished code PostgreSQL — schema design, query optimization, migrations in a production context AWS experience — you've deployed and operated production workloads on AWS (ECS/EKS, RDS, Lambda, S3) and can make informed infrastructure decisions Comfort working in ambiguous, greenfield settings — you define scope with stakeholders rather than waiting for pre-scoped tickets Nice-to-Have: Infrastructure as Code (Terraform) Healthcare, diagnostics, or regulated-environment experience Security hardening practice — threat modeling, dependency scanning, secure defaults Observability tooling (CloudWatch, Prometheus, Grafana) CI/CD pipeline design (GitHub Actions or similar) Our offer: Permanent full-time contract (B2B contract) Ability to work entirely remotely or in one of our cool offices around Poland International project environment - challenging and rewarding projects Access to private medical service, life insurance, and multisport card Access to training and certificate courses (including free access to Udemy training platform) Cafeteria Benefits System - vouchers for purchases and sevices Awesome company events and parties

🏢 Summary: Senior Full-Stack Engineer role focused on building AI-powered products and internal platforms using Python and modern frontend frameworks. The position involves developing cloud-native systems, contributing to agentic AI initiatives, and delivering secure, production-grade solutions handling sensitive data. You will work in agile teams to create end-to-end features across backend, frontend, cloud, and AI components. 🗂️ Requirements: Bachelor’s or Master’s degree in technical field, Minimum 7 years of software development experience, Senior-level experience in large tech environment, Strong backend experience with Python and FastAPI in production, Solid frontend experience with Vue or other modern JavaScript framework, Hands-on experience with AWS, Azure, or GCP, Experience with Docker or Kubernetes, Experience with SQL and NoSQL databases, Experience with messaging queues, Practical experience with AI systems in production, Understanding of agentic AI concepts or architectures, Knowledge of engineering best practices and secure coding 📃 Skills: Python, FastAPI, Django, Vue, React, Angular, Svelte, AWS, Azure, GCP, Docker, Kubernetes, SQL, NoSQL, Pinecone, AzureAISearch, CrewAI, MicrosoftAgentFramework, AWSAgentCore, A2A, MCP 🏢 Description: We’re looking for a Senior Full‑Stack Engineer to help build AI‑powered products and internal platforms used across the company. You’ll join a fast‑moving engineering team where AI accelerates development, improves productivity, and shapes how new solutions are delivered. Security, compliance, and high engineering standards are essential, especially for production systems handling sensitive data. What you’ll do Build end‑to‑end features using Python (FastAPI, Django) and modern frontend frameworks, with a preference for Vue, though React, Angular, or Svelte are also welcome. Develop cloud‑native systems on AWS, Azure, or GCP, working with containers, databases, and messaging systems. Contribute to AI initiatives, including agentic systems, vector search, and prompt‑driven workflows. Work in small, agile squads with the flexibility to move between projects as priorities evolve. Required qualifications Bachelor’s or Master’s degree in a technical field. At least 7 years of software development experience, including senior‑level work in a large tech environment. Strong backend experience with Python and FastAPI, with proven production delivery. Solid frontend experience with Vue or another modern JavaScript framework. Hands‑on experience with cloud platforms, Docker or Kubernetes, SQL and NoSQL databases, and messaging queues. Practical experience working with AI systems or AI‑driven features in production environments. Understanding of agentic AI concepts or hands‑on exposure to agent‑based architectures. Strong grasp of engineering best practices, design patterns, and secure coding. Clear communication skills and the ability to explain technical concepts. Preferred qualifications Experience with vector databases such as Pinecone or Azure AI Search. Knowledge of prompt engineering, context management, and LLM‑driven workflows. Experience with agentic AI frameworks such as CrewAI, Microsoft Agent Framework, or AWS Agent Core. Familiarity with agentic protocols like A2A or MCP. Background in distributed systems and microservices. Experience working in agile teams. Why join You’ll work on real AI products, help shape an evolving agentic ecosystem, and contribute to a modern engineering environment where innovation meets strong security and compliance standards. Your work will directly influence how AI is used across the organization.

🏢 Summary: Senior / Staff Full Stack Engineer role focused on building and scaling an AI-driven product platform in a fully remote setup. The position involves developing React/TypeScript frontend experiences and Python-based backend APIs to support document processing, retrieval systems, and structured AI/ML outputs. The engineer will integrate frontend, backend, and AI workflows into a reliable, testable product experience. 🗂️ Requirements: 5+ years full stack engineering experience, Strong Python backend API development experience, Strong React and TypeScript production experience, Experience with modern API frameworks (e.g. FastAPI), Experience designing and consuming API contracts and structured JSON, Experience with asynchronous workflows and background jobs, Testing experience covering edge cases and API behavior, Understanding of AI/ML product workflows 📃 Skills: Python, React, TypeScript, FastAPI, API, JSON, AI, ML, LLM, OpenAI, Gemini, Anthropic, Embeddings, Vector, Firebase, Firestore, GCP, CloudRun, CloudSQL, Neo4j 🏢 Description: We are looking for a Senior / Staff Full Stack Engineer with strong Python and React experience to build and scale an AI driven product platform in a fully remote setup. The role focuses on frontend experiences, backend APIs, document processing, retrieval systems, and structured AI / ML outputs. ✅ Your responsibilities: Building frontend experiences in React and TypeScript for evidence review, workflow status, recommendations, and decision outputs. Developing backend APIs in Python, ideally with FastAPI, for document upload, asynchronous processing, job status, retries, partial success, and structured results. Connecting frontend, backend, data workflows, retrieval systems, and AI generated outputs into a reliable product experience. Building product features that make AI outputs easier to inspect through source references, confidence signals, warnings, and clear error states. Working with structured data, documents, tables, financial metrics, and normalized evidence flows. Writing tests around API contracts, edge cases, error cases, and realistic user workflows. 🧠 Our requirements: 5+ years of professional full stack engineering experience. Strong experience with Python and backend API development. Strong experience with React and TypeScript in production applications. Experience with modern API frameworks, ideally FastAPI or similar. Understanding of AI / ML product workflows or strong interest in building software around AI outputs. Experience designing and consuming API contracts, schemas, and structured JSON payloads. Comfort with asynchronous workflows, background jobs, retries, partial failures, and user visible process status. Good testing habits, especially around edge cases, failure cases, and API behavior. ⭐ Nice to Have: Experience with AI / ML product workflows, including retrieval systems, embeddings, vector search, LLM based applications, or LLM APIs such as OpenAI, Gemini, Anthropic/Claude. Experience with data heavy products, including data workflows, document processing, data normalization, or working with structured evidence. Experience with cloud and data infrastructure, ideally Firebase, Firestore, Google Cloud Platform, Cloud Run, Cloud SQL, vector search, or Neo4j. 🌟 What we offer: 100% remote work Opportunity to work on modern ML/AI infrastructure Private healthcare and Multisport Life insurance Real influence on technical decisions and architecture Exposure to cutting-edge technologies Collaborative and supportive team environment

🏢 Summary: Senior Full Stack Engineer role with end-to-end ownership of user-facing product features across frontend and backend. The position focuses on turning vague product goals into shipped, production-ready solutions with strong product judgment, code quality, and performance. You will work across UI, APIs, and data flows while leveraging AI tools to accelerate development and improve engineering workflows. 🗂️ Requirements: Senior-level experience shipping production web applications, Strong frontend expertise with React and TypeScript or modern equivalent, Ability to design and implement APIs and backend logic, Experience building and maintaining data flows in production systems, Experience instrumenting applications for production monitoring, Ability to write and maintain automated tests, Experience using AI tools in daily development workflow, Strong understanding of performance and reliability in web applications 📃 Skills: React, TypeScript, JavaScript, Python, Node.js, APIs, REST, HTML, CSS, Testing, AI, Git 🏢 Description: About Shelf Shelf builds software that helps enterprises make AI work in the real world. We build products people depend on, which means product judgment, engineering quality, and execution speed all matter at the same time. About the Role This role is for a senior full stack engineer with strong product instincts. You will own meaningful product slices end to end: understand the problem, shape the approach, build the frontend and backend pieces, ship them, and improve them based on real usage. We want someone who is equally comfortable improving a user flow, shaping an API, and closing the loop on quality in production. This is a product engineering role with real end-to-end ownership. Location – Warsaw, work from the office What You Will Own Build and ship user-facing product features across frontend and backend boundaries. Turn rough product goals into practical solutions with good scope, sensible trade-offs, and strong execution. Work comfortably in UI, application logic, APIs, and data flows rather than stopping at team boundaries. Partner closely with product and design while still being able to move when the spec is incomplete. Improve usability, clarity, performance, and reliability, not just feature completeness. Instrument what you ship so we can learn from production behavior and iterate quickly. Use AI tools daily to move faster and help improve internal workflows, tooling, and engineering leverage. Keep the bar high on code quality, testing, and ownership after launch. What Strong Performance Looks Like You can take a vague product problem and turn it into a shipped, well-reasoned solution. Your features feel coherent end-to-end because you care about both implementation and product quality. You do not treat frontend and backend as separate worlds; you use both to solve the actual problem. You bring momentum. Work moves because you are on it. What We Are Looking For Strong senior-level experience shipping production web products. Strong frontend ability with React and TypeScript or an equivalent modern web stack. Real backend ability. You do not need to be backend-only, but you can design and ship APIs, backend logic, and data flows when the product needs it. Strong product sense. You notice awkward flows, weak defaults, and unnecessary complexity, and you improve them. Good judgment about scope, iteration, and technical trade-offs. Clear communication and comfort working across engineering, product, and design. AI-native working style. You already use AI tools as part of daily implementation and problem solving, and you are excited to improve how engineering work gets done. Strong Plus Experience with AI-powered product experiences such as chat, search, recommendations, workflows, or agent-like systems. Experience with Python, Node.js, or both on the backend. Experience owning product areas with limited oversight. Strong feel for performance, accessibility, and production quality in complex web applications. How We Evaluate Fit We care more about end-to-end ownership, product sense, and the ability to ship meaningful work than a perfect match to every framework on paper. If you are the kind of engineer who can make a product better from multiple angles, we want to talk. What Shelf Offers B2B contract. Stock options. MacBook Pro. A strong AI-native engineering environment with modern tools and room to experiment.

🏢 Summary: Senior Full-Stack React and Python Developer role focused on building and enhancing an AI-driven investment research platform. The position involves developing React frontend features and Python/Node.js backend services, integrating REST APIs, and ensuring high-quality, scalable solutions in a fintech environment. Fully remote within the EU. 🗂️ Requirements: 6+ years Full-Stack development experience, Strong React experience with hooks, Backend development in Python or Node.js, Experience building and integrating REST APIs, Understanding of state management patterns, Ability to work across frontend and backend, Experience with code reviews, Strong debugging skills across full stack, Fluent English, Legal right to work in the EU 📃 Skills: React, JavaScript, Python, Node.js, REST, APIs, HTML, CSS, Git 🏢 Description: Empower innovation at the forefront of financial technology — shape the future of AI-driven investment research! EU-based opportunity with a remote work model (up to 5 days per week). As a Senior Full-Stack React and Python Developer , you will be working for our client, a pioneer in building AI-powered infrastructure for investment research. You will contribute to automating expert interviews, managing global expert networks, and delivering critical insights to hedge fund clients under strict compliance standards. Join a growing platform that is redefining data-driven finance and unlock new career heights in a cutting-edge environment. Your main responsibilities: Build and iterate on React-based frontend features for our web application. Develop and maintain backend services in Python and/or Node.js. Integrate frontend components with REST APIs and data services. Participate in code reviews and promote engineering best practices. Debug issues across the entire stack—from UI rendering to API behavior. Collaborate with design and product teams to implement clean, user-friendly interfaces. You're ideal for this role if you have: At least 6 years of experience as a Full-Stack Developer, ideally within fintech or data-heavy environments. Strong React experience with modern hooks-based development. Backend development experience in Python and/or Node.js. Comfort working across the full stack and owning features end-to-end. Solid understanding of REST APIs and state management patterns. Clean coding habits and familiarity with code review processes. It is a strong plus if you have: (optional) Experience with TypeScript on both frontend and backend. Knowledge of cloud deployment platforms such as Azure or AWS. Background in financial technology, data-intensive applications, or compliance-focused products. Experience with testing frameworks like Jest or Pytest. Language Required for the role: Fluent English Eligibility for the role: Only candidates with an existing legal right to work in the European Union will be considered for this role. #MAKEYourCareerBETTER Interested? Apply now and include your CV (preferably in English) along with a statement confirming your consent to the processing and storage of your personal data.

🏢 Summary: Senior Fullstack Engineer role focused on delivering full-stack solutions within an AI-integrated SDLC where AI is embedded across planning, development, review, testing, and deployment. The position combines backend and frontend engineering with AI orchestration, automation, and cloud-native architecture in a remote-first setup. The engineer will also evolve shared AI toolchains and contribute to architectural and code quality standards. 🗂️ Requirements: Team-level AI-integrated SDLC experience across planning, development, review, testing, deployment, Shared AI toolchain management under version control, Hands-on use of Claude Code, GitHub Copilot, Cursor or equivalent as team tools, Building and maintaining custom AI skills and sub-agents for team use, Experience with parallel AI agent orchestration, Spec-driven development using OpenAPI, ADRs, PRDs as AI context, AI-assisted code review integrated into PR process, Working knowledge of AI orchestration frameworks, Backend development with .NET / C# and ASP.NET Core, Frontend development with TypeScript and React or Angular, Experience with SQL databases and ORM frameworks, Experience with Docker and Kubernetes, Experience with CI/CD pipelines, Experience with cloud platforms (Azure, AWS, or GCP) 📃 Skills: C#, .NET, ASP.NET, SQL, SQLServer, PostgreSQL, EFCore, OAuth, JWT, Python, Java, Node.js, TypeScript, JavaScript, React, Angular, LangChain, LlamaIndex, CrewAI, Docker, Kubernetes, GitHubActions, AzureDevOps, Azure, AWS, GCP, OpenAPI, CQRS, DDD, EventSourcing, Microservices 🏢 Description: We are looking for a Senior Fullstack Engineer who combines deep technical expertise with real, team-level experience working in an AI-integrated software development lifecycle. Individual use of AI coding assistants is not sufficient for this role. We are specifically looking for engineers who have worked in teams where AI was embedded into every phase of delivery — from planning and design through development, review, testing, and deployment. We follow a remote-first setup with no mandatory regular office visits for this position. From time to time, you may be invited to join in-person meetings in one of our offices (Warsaw, Lodz, Wroclaw, Gdansk, or Bialystok), for example for client visits or team reunions. AI-First Requirements Experience working in an AI-enabled engineering team is mandatory — not a personal workflow preference. You have been part of a team where AI was systematically embedded across all delivery phases: planning, development, review, testing, and deployment. You can speak from direct experience about how it worked, what failed, and what you would change. Specific mandatory requirements: Team-level AI-integrated SDLC experience — shared toolchain, shared configurations, shared assets under version control Hands-on with Claude Code, GitHub Copilot, Cursor, or equivalent as a team tool, not only personal usage Built and maintained custom skills and sub-agents used across a team, not just personally Experience with parallel agent orchestration for concurrent workstream execution Disciplined plan → review plan → execute approach with AI involved at every phase Maintained shared prompt libraries, skill repositories, or agent configurations in version control AI-assisted code review integrated into the PR process: CodeRabbit, Copilot review, or similar Experience with spec-driven or document-driven development where structured specifications (OpenAPI, ADRs, PRDs) serve as AI context inputs, not just human references Working knowledge of at least one AI orchestration framework: LangChain, LlamaIndex, Microsoft Agent Framework, CrewAI, or equivalent Automation-first mindset: proactively identify repetitive or inefficient parts of current work and automate them using AI and other available tools. Cost-aware AI usage: understanding how AI credits are consumed across different tools, models, and workflows, and ability to choose the most appropriate model or approach for each task. Technical Requirements Backend: .NET / C#, ASP.NET Core, SQL Server / PostgreSQL, EF Core, OAuth 2.0 / JWT. Python, Java, or Node.js is a strong plus. Frontend: TypeScript, JavaScript, React(preferable) and/or Angular, state management, async patterns, frontend testing. Architecture: Full spectrum from monolith to microservices — DDD, CQRS, Event Sourcing, event-driven design, message brokers. Infrastructure: Docker, Kubernetes, CI/CD (GitHub Actions / Azure DevOps), Azure / AWS / GCP, structured observability. Responsibilities Deliver full-stack features to a high standard of quality, performance, and reliability Contribute to architectural decisions and system design trade-offs Evolve and maintain the team's shared AI toolchain across all SDLC phases Conduct code reviews including AI-assisted tooling; uphold and enforce engineering best practices Proactively surface risks, bottlenecks, and security concerns Communicate and collaborate directly with clients in English Mentor engineers on both technical fundamentals and AI-augmented workflow practices Professional Qualities Ownership mindset · Strong written and verbal English · Comfortable in client-facing roles · Raises the AI workflow maturity of those around them

🏢 Summary: Senior Backend Engineer role focused on building and scaling backend systems for an AI-driven product that transforms complex government data into actionable insights. The position involves designing data ingestion, processing pipelines, and distributed infrastructure from scratch, with full ownership from architecture to production. You will work closely with a small senior team to deliver scalable, production-ready systems. 🗂️ Requirements: 6+ years of Backend Engineering experience, Experience in JVM ecosystem, Experience in product companies (B2B SaaS preferred), Experience designing and owning backend systems in production, Strong knowledge of system design and scalability, Experience building asynchronous or distributed systems, Ability to make and justify technical decisions, Fluency in English, Valid work authorization in Europe or LATAM 📃 Skills: Kotlin, Java, JVM, SQL, GCP, Messaging, Queues, DistributedSystems, SystemDesign, DataPipelines, LLMs, AI 🏢 Description: About the role We’re looking for a Senior Backend Engineer to join our early team and help build our product from zero to one. You’ll work on a product that helps companies navigate complex government data, from contracts and grants to market signals and turn it into actionable insights using AI. On the backend side, this means working on data ingestion, processing, and the infrastructure that powers search and AI-driven workflows at scale. You’ll collaborate closely with a small, senior team and have real ownership, from shaping solutions to shipping them to production and improving them over time. You might be a fit if you: Must have: 6+ years of experience as a Backend Engineer, preferably in the JVM ecosystem (we use Kotlin on the backend) Experience working in product companies (B2B SaaS preferred) with direct impact on shipped features Experience working in small companies or startups would be a strong advantage Experience designing and owning backend systems in production (from initial design to deployment and ongoing improvements) Strong understanding of system design, including scalability, failure handling, and trade-offs Experience building asynchronous or distributed systems (e.g. messaging, queues, event-driven systems) Ability to make and justify technical decisions, not just implement given solutions Fluency in written and spoken English Nice to have: Experience with large-scale data processing, scraping, or data pipelines Experience working with LLMs / AI-related systems Experience with GCP or similar cloud environments How We Work Build Bridges to Help Customers Win - We pride ourselves on being obsessively customer-centric. Shooting Star Speed - We move with extreme speed. We value momentum, decisiveness, and the ability to accelerate when it matters. Fun Is a Feature - Fun is a Feature means we intentionally design Starbridge to be an energizing place to do hard work. Joy, humor, and camaraderie make great teams faster, sharper, and more resilient. In the Arena - We believe the best ideas come from living close to the work, feeling the friction, hearing the nuance, and experiencing the details firsthand. Benefits include: Competitive salary + early-stage equity Unlimited PTO Regular off-sites (NYC + global locations) Interview Process We move fast — really fast. Getting back to someone today beats tomorrow, and our interview process reflects that mindset. Please keep us posted on your timeline so we can move quickly and speed things up where needed. After submitting your application, the team reviews your CV and statement of exceptional work. If your application passes this stage, you will be invited to a 30-minute interview during which a member of our team will make sure you're a good fit for the role. You will have the opportunity ask questions and learn more about the role as well. We'll then send you a programming challenge that consists of two parts: LeetCode and SQL. Beyond that step, you will enter the main process, which consists of three interviews: System design exercise hands-on. Live coding in Java/Kotlin. Product thinking and past work. All interviews will be conducted via Google Meet. Eligibility to Work in Europe or LATAM: Candidates must hold valid authorization to work in the country where they will be based. At this time, we are unable to offer visa sponsorship or assist with work permit applications.

🏢 Summary: Senior Fullstack Engineer role focused on designing and scaling production-grade web systems, owning the full product experience from backend to frontend. The position combines product thinking with engineering, emphasizing AI-augmented features and modern fullstack architecture. You will work on complex, mission-critical applications with strong autonomy and technical ownership. 🗂️ Requirements: 5+ years of experience building complex web applications, Strong proficiency in Python or Ruby, Strong proficiency in Vue.js or React.js, Solid understanding of SQL and PostgreSQL, Experience with CI/CD pipelines, Experience with cloud environments, Experience using AI/LLM tools in development workflows, Fluent English (C1) 📃 Skills: Python, Ruby, Vue.js, React.js, PostgreSQL, SQL, AWS, Docker, CI/CD, Claude, Cursor 🏢 Description: At Upside , we’re partnering with ambitious companies across the globe to solve complex, meaningful problems through technology. We work in focused teams, combining engineering, product thinking, and design, to deliver outcomes, not just output. Open-source is a strategic part of our work. We build and maintain a number of open-source projects that support our clients and internal R&D. Our latest release is Enthusiast , a customizable agentic AI toolkit for e-commerce. What it means for you You’ll have a "Founder" mindset. You won’t just build a UI or a database - you’ll own the entire product experience. You’ll be a technical partner to stakeholders, helping them understand what’s possible with modern tech and AI. You’ll have the autonomy to experiment across the stack and the responsibility to deliver tools that actually solve business problems. You’ll work at the intersection of product thinking and engineering, deploying AI-augmented features across the entire stack. Role Overview As a Senior Fullstack Engineer, you’ll design and scale resilient systems from the ground up. You’ll bridge the gap between backend logic and frontend experience, ensuring a seamless, production-grade product. Responsibilities End-to-End Ownership: Lead the design and implementation of both backend systems and frontend interfaces. Proactive Solutions: Don't just flag blockers—come with proposals and experiments to bypass them. Consulting: Translate complex business needs into elegant, scalable fullstack architecture. Engineering Standards: Advocate for code quality, security, and performance across the entire repo. Continuous Improvement: Constantly evaluate new tech (especially AI/LLM) to improve delivery. Requirements Experience: 5+ years of building complex web applications. Backend: Strong proficiency in Python or Ruby. Frontend: Mastery of Vue.js or React.js . Infrastructure: Solid understanding of SQL (PostgreSQL), CI/CD, and cloud environments. AI-Native: You use tools like Claude or Cursor to build better and faster. English: Fluent (C1) for direct client collaboration. Tech Stack: Python, Ruby, Vue.js , React.js , PostgreSQL, AWS, Docker. Value Proposition Built for the long run We hire for the company, not just a project - looking for passion driven engineers who want to grow with Upside over time Small teams, real accountability. 3-9 people per engagement. We're small by design. That means your decisions carry weight and you are visible. Mission-critical work: We handle complex  projects that move the needle for international brands. Our clients are scaling companies, established international brands, and large institutions. The systems you build will be under real load, with real stakes. Real Ownership: You take part in the decision making process on technology and implementation..You’re empowered to take initiative, experiment, and drive solutions that create real impact. No Micromanagement: We trust you to own your work and deliver outcomes - no unnecessary oversight. Collaborative R&D: Contribute to targeted Open-source projects and internal AI research. Growth through challenges: Complex problems and direct client exposure means you’ll grow by action. Applied AI as a first-class discipline. We don't bolt AI onto projects as an afterthought. You'll identify where it genuinely moves the needle and lead the implementation - on client work and on our own open-source tooling. The tools you want. If something makes you faster or sharper, we want you using it. Transparent progression path. We have defined engineering levels with clear criteria - you'll know exactly what each role looks like, and what it takes to get from one to the other. No ambiguity, no waiting for someone above you to move on If you didn't find all the information you were looking for, have a look at our handbook - it covers a variety of different matters that could be important at this stage. If there's anything else we did not mention that you're interested in - share your thoughts with us careers@upsidelab.io Compensation & Location Salary: Senior Engineer: 20 800 - 25 900 PLN net + VAT Lead Engineer: >25 900 PLN net + VAT Location: Office in Kraków, hybrid, fully-remote.