June 17, 2026

Fullstack Engineer

Senior • Hybrid

25,000 - 30,000 PLN

Krakow, Poland

The role

We’re hiring senior full-stack engineers who can own the engineering judgement behind our product. Our SDLC is heavily AI-enabled: often you’ll be handed a working prototype rather than starting from a blank file. Your job is to ensure the logic and performance are sound before it ships — and to own it in production once it does, including fixing bugs.

This is not a role where AI does the thinking for you. AI accelerates the build, and you act as the guardrail. You decide whether something is correct, performant, secure, and maintainable enough for enterprise customers — and you’re accountable once it’s live.

What you’ll do

  • Take AI-generated prototypes from proof-of-concept to production-ready by validating logic, identifying edge cases, optimizing performance, and hardening weak points.
  • Own features in production: you ship it, you own the bugs, and you fix them.
  • Review AI-generated output to real engineering standards, as you would a strong junior engineer’s work.
  • Work across the stack in Python on the backend (REST APIs, data modelling, integrations) and React + TypeScript on the frontend.
  • Ensure security, data integrity, performance, and high-quality user experience for enterprise customers.
  • Raise engineering standards through thoughtful reviews, mentorship, and improving AI-assisted development practices.

How we work

Our development process is heavily enhanced by AI, but engineers own every decision. AI writes much of the first draft; engineers decide what’s right, catch what’s wrong, and remain accountable for what ships. We mainly use Claude Code with additional skills and guidelines on top.

What we’re looking for

  • 5+ years building and shipping production software as a full-stack engineer.
  • Strong Python skills (we use Django; experience with mature Python web frameworks transfers well).
  • Strong React and TypeScript skills.
  • Ability to identify flawed logic, inefficient queries (e.g., N+1), missing edge cases, and scalability risks.
  • Experience with relational data modelling, clean REST API design, and reasoning about performance and scale.
  • Strong ownership mindset and accountability for production systems.
  • Sound judgement on trade-offs and engineering quality.
  • Openness to AI-enabled development workflows.
  • Clear communication in English.

Nice to have

  • Experience in B2B / enterprise SaaS, especially security, compliance, or data-heavy products.
  • Experience with embedded analytics, data warehousing, or BI tooling.
  • Experience leading AI initiatives that improved team velocity.

Vatix is an equal opportunity employer. We welcome applicants from all backgrounds.

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The US defence industrial base — distributors and manufacturers managing billions of dollars in supply chain — still runs on infrastructure built in the 1980s, stitched together with email threads, supplier quotes, PDFs, government solicitations, and archaic ERP exports. We're changing that. Our platform eliminates the manual bottlenecks slowing down critical national security workflows, helping defence distributors and manufacturers quote faster, win more contracts, and deliver the components that keep allied defence forces operational. We're at seed stage, moving fast, and building a small core engineering team to scale the platform. ABOUT THE ROLE We're looking for a Full Stack Engineer to join the core platform engineering team and contribute directly to the development, scalability, and reliability of mission-critical software supporting defence and supply chain operations. You'll work closely with engineering leadership, founders, and customer-facing deployment teams to design, build, and maintain systems that integrate with complex legacy environments and support high-value, high-impact workflows. No two days will be the same — from integrating with legacy government interfaces to architecting dynamic workflows, the scope is wide and the stakes are real. Onboarding includes an on-site implementation. Expect late nights and direct customer pressure — everyone on the platform team goes through it, because experiencing forward-deployed reality is how you build software that actually works in the field. WHAT YOU'LL WORK ON Full-stack platform development Design, develop, and maintain full-stack application functionality across frontend interfaces, backend services and APIs, and database schemas and data models. Legacy system integrations Implement integrations with external systems including legacy government and enterprise platforms — ERPs, government procurement interfaces, and everything in between. Customer-driven feature delivery Collaborate with forward-deployed teams to translate customer requirements into production-ready features that drive measurable revenue outcomes for clients. Code quality and standards Ensure code quality through best practices, testing, documentation, and code reviews. Set the standard for customer-centric engineering excellence — code is a means to an end, and you build with that in mind. Team mentorship and onboarding Support the onboarding and technical development of new engineering team members as the team grows. WHAT WE LOOK FOR A track record of shipping Experience delivering real projects and products to production. You've owned things end-to-end and have the scars to show for it. TypeScript and JavaScript fluency Strong proficiency in TypeScript and JavaScript, plus solid experience with at least one frontend framework — React, Svelte, Next.js, or similar. SQL and database design Solid knowledge of SQL databases, preferably PostgreSQL. Comfortable designing schemas and reasoning about data models. Software engineering best practices Strong understanding of testing, documentation, code review, and the longer-term cost of shortcuts — while also knowing when pragmatic compromises are the right call. High accountability in fast-moving environments You set reliable deadlines and meet them. When millions of dollars depend on a delivery date, you treat that seriously — and you communicate clearly when something is at risk. THE TEAM A small, tight-knit engineering team working directly with founders and customer-facing deployment strategists. The structure is flat, the feedback is direct, and the work has real-world consequence. You'll have genuine ownership from day one — both in terms of equity and the code you're responsible for. COMPENSATION & BENEFITS Salary $75,000 – $150,000 depending on experience. Equity 0.05% – 0.3% real equity. A meaningful slice at seed stage. Work model Remote, based in Warsaw.

Technology

Loop Returns

Senior Software Engineer

Senior

Hybrid

Columbus, OH

155,004 - 195,000 USD

🏢 Summary: Senior Software Engineer role focused on owning complex, cross-functional initiatives across the full stack, from architecture to production. The position emphasizes AI-first engineering practices, leveraging AI agents for planning, code generation, and review while maintaining accountability for production outcomes. You will design scalable systems, lead technical initiatives, and mentor engineers while working with modern cloud and web technologies. 🗂️ Requirements: 5+ years of experience building web applications, backend services, and APIs, Strong experience with PHP and Laravel, Experience designing and implementing full-stack features (backend, APIs, frontend), Ability to design system architecture and evaluate technical trade-offs, Experience leading technical initiatives, Experience mentoring junior engineers, Experience working with AI coding agents in development workflows, Experience monitoring and owning production systems 📃 Skills: PHP, Laravel, Vue.js, MySQL, DynamoDB, Kubernetes, AWS, Serverless, APIs, Lambdas, AI, Claude, Cursor 🏢 Description: About the Role: Loop is looking for a Senior Software Engineer to take meaningful ownership of complex, cross-functional work, from architecture and design through production. You'll build scalable solutions, influence technical direction, and make the engineers around you better. AI at Loop Engineering: Engineering at Loop is AI-first, not aspirationally, but operationally. Every engineer is provisioned with Claude Code and Cursor, and we expect AI agents to be your default starting point before you open a file. The role has shifted: you are not primarily a writer of code. You are the judgment layer, the person who determines what should be built, validates that what was built is correct, and owns the outcome in production. At the senior level, that judgment extends beyond your own work to the systems, standards, and people around you. You're not just using AI well — you're helping your team develop the habits and instincts to use it well too. Our Blended Work Environment: We work from our HQ in Columbus, OH, and are distributed throughout the United States, select Canadian provinces, United Kingdom, and Australia. For this position, we're open to Columbus, OH; Boston, MA; Chicago, IL; Austin, TX; Los Angeles, CA; or fully remote. Our Tech Stack: PHP/Laravel, Vue.js, MySQL, DynamoDB, Kubernetes, AWS, Serverless. Our hiring process is tech-stack agnostic. What You'll Do: - Design and implement complex, high-quality features across the full stack: backend services, APIs, lambdas, and frontend. Translate ambiguous requirements into clear technical designs and own the trade-offs. - Start with the agent, not the editor. Invest time in planning and intent articulation. The quality of your prompt is the quality of your output. - Review AI-generated code with the same rigor you'd apply to any code. Plausible is not the same as correct. At this level, you're also setting the standard for how your team does this. - Set the standard for AI-assisted code review on your team. Model what good verification looks like, not just for your own PRs, but in how you give feedback on others' AI-generated work. - Lead small to medium-sized technical initiatives: provide direction, surface dependencies early, and keep stakeholders informed without being asked. - Mentor and develop more junior engineers through code review, pairing, and direct feedback. Making the people around you better is part of the job, not a bonus. - Make reversible decisions fast and flag the irreversible ones early. Operational trust means others can plan around your delivery. - Make the system around you more effective, not just your own output. Propose improvements to code quality, processes, and team norms, and follow through on them. Your Experience: - 5+ years building web applications, backend services, and APIs. Strong PHP/Laravel experience preferred. - You use AI agents as your default starting point and can describe your actual workflow: how you plan, prompt, evaluate output, and decide where to spend your review time. You own what ships, regardless of how it was generated. - You have a point of view on where AI helps and where it gets engineers into trouble, and you actively help your team navigate that line. - You track how your code behaves in production, not because someone asks you to, but because you own the outcome. You've caught regressions before support tickets did. - You can evaluate architectural trade-offs and make defensible decisions, not just implement what you're handed. - You have examples of leading technical initiatives, mentoring engineers, and driving cross-functional alignment. - You operate with intensity and hold a high bar for your own work and for the people around you. You give direct feedback, ask for help early, and respond to setbacks with ownership rather than withdrawal. - You've worked closely with product managers and design teams, and you've had the hard conversations with peers, stakeholders, or leaders, with directness and care.

Technology

TechTree

Fullstack Software Engineer (FE leaning)

Senior

On-site

Warsaw, Poland

100,000 - 150,000 USD/yr

🏢 Summary: End-to-end software engineering role focused on building and shipping high-quality product features across frontend and backend in a fast-moving, autonomous team. The position emphasizes pixel-perfect UI/UX, strong architectural thinking, and full ownership from design to deployment. Engineers operate with high trust and direct impact on a learning and research-focused product. 🗂️ Requirements: Expert-level software engineering experience, Strong proficiency in TypeScript, Experience with SvelteKit for frontend development, Experience with Node.js for backend development, Experience with Fastify, Experience with PostgreSQL, Experience with DDD patterns, Experience with CQRS patterns, Experience with Playwright for testing, Ability to build pixel-perfect UI implementations, Ability to design and ship end-to-end features across frontend and backend, Experience working with queues, Basic proficiency in Python for ML components 📃 Skills: TypeScript, SvelteKit, Tailwind, DaisyUI, Playwright, Node.js, Fastify, PostgreSQL, Python, DDD, CQRS, Queues 🏢 Description: ABOUT THE ROLE We're looking for an expert software engineer with an exceptional eye for UI/UX to join a small, high-trust engineering team. You'll own features end-to-end — from pixel-perfect frontend work to shipping backend functionality when needed. This is not a siloed role. You'll move fast, make real decisions, and have direct impact on a product used by people who care deeply about learning and research. We don't have managers. We have engineers who own their work. TECH STACK The stack is heavily TypeScript. On the frontend: SvelteKit, Tailwind, DaisyUI, and Playwright, with DDD and CQRS patterns. On the backend: Node.js, Fastify, PostgreSQL, and queues. ML components are in Python. The stack is pragmatic, not dogmatic — tools may shift as the product evolves. WHAT WE LOOK FOR Elite communication You set accurate expectations and live up to them. No surprises, no ambiguity about status or blockers. Deep resilience Bugs, crises, tough reviews — you have a large buffer before stress impacts your output. You don't crack under pressure. No ego We're here to build something great, not to manage insecurities. The best idea wins, regardless of who had it. Product mastery You understand the engineering principles behind the best software ever made — and care deeply about the difference between good and great. Independent and obsessive by nature You go deep on everything you touch. You're a lifelong learner who can't help but care about quality. Being an ex-founder is a bonus. ENGINEERING CULTURE Optional code reviews We trust you. Merge when you're ready. Ask for a second pair of eyes when you want one. Radical autonomy We don't second-guess your decisions. You own the call. High-bandwidth collaboration Constant communication means everyone has context without formal gates or status meetings. Direct feedback Code reviews are blunt, concise, and respectful. We say what we mean. Ruthless efficiency We aggressively adopt any tool — AI included — that increases speed and leverage. Limited frontend test coverage Supplemented by strong architecture and top talent, not bureaucratic QA processes. RECRUITMENT PROCESS Recruiter screening — a short intro call to align on basics. 1-on-1 with the engineering lead — a conversation about how you think and work. Technical challenge (~4 hours) — use AI, Google, or any resource you need. We care about the result, not the method. One-month paid contract — with the possibility to extend indefinitely. Honest, frequent feedback throughout so you always know where you stand. COMPENSATION & BENEFITS Salary $100,000 – $150,000 depending on experience. Equity and profit share Core team members receive both equity and profit share as part of the compensation package. Unlimited PTO Use your own judgement — we won't count days. Steep learning curve You'll grow faster here than almost anywhere else — by design, not accident. Real ownership No managers capping your authority. You own your work end-to-end, with the full trust of the team behind you.