Senior Full-Stack Engineer (TypeScript, React, Node.js)
About The Position
A seed-stage B2B SaaS company is building subscription infrastructure for e-commerce, including billing, checkout, and developer tools. The Senior Full-Stack Engineer will own features from idea to release, working across frontend and backend and collaborating directly with designers and founders. The engineer will also help shape the product architecture as the company grows. The role involves building full-stack features in TypeScript, using React on the frontend and Node.js on the backend. It includes developing merchant-facing subscription, billing, and checkout flows, as well as improving developer-facing APIs, documentation, integrations, onboarding, and error messages. The engineer will work from Figma designs, contribute practical UX improvements, and maintain a simple, observable, and maintainable architecture.
Requirements
- Fluent Polish and residence in Poland.
- At least 5 years of professional software engineering experience, mostly in product or SaaS companies rather than only agencies or consulting.
- Strong production experience with TypeScript and Node.js, including features used by real customers.
- Production experience with React.
- Experience taking at least one customer-facing feature from requirements to release.
- Comfort working from Figma designs.
- Ability to work independently in an early-stage team without detailed specifications.
Nice To Haves
- Experience with Next.js, or Vue and Nuxt.
- Experience with Fastify, Express, or NestJS.
- Payments or subscriptions experience, including recurring billing, payment providers, invoicing, proration, or dunning.
- E-commerce experience with Shopify, WooCommerce, Magento, or headless commerce.
- Experience with public APIs, SDKs, webhooks, or developer documentation.
- Startup experience, especially in teams with fewer than 200 people.
- Hands-on use of AI and LLM tools such as Cursor, Copilot, Claude, or OpenAI.
Responsibilities
- Build and ship full-stack features in TypeScript using React on the frontend and Node.js on the backend.
- Own features end to end: clarify requirements, propose an approach, build, test, release, and assess impact.
- Build clear and reliable merchant-facing subscription, billing, and checkout flows.
- Improve APIs, documentation, integrations, onboarding, and error messages for developers.
- Turn Figma designs into clean, accessible UI and suggest practical UX improvements.
- Keep the architecture simple, observable, and maintainable without over-engineering.
- Conduct code reviews, write automated tests, and maintain useful documentation.
- Use AI coding tools where they save time or improve quality.
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What This Job Offers
Job Type
Full-time
Career Level
Senior
Education Level
No Education Listed
