Senior Full-Stack Developer (MERN) - Senior Software Lead Engineer

Lead Full-Stack Developer We're a fast-growing European startup that matches students/flexible workers with local businesses in Belgium. As a Lead Full-stack Developer you will work across continents. You'll own the technical direction of our platform end-to-end architecture, APIs, integrations, and performance while mentoring the team and working directly with stakeholders.What you'll do•⁠ ⁠Own architecture decisions across the stack: Node.js, Nest.js, React.js/Next.js, TypeScript•⁠ ⁠Design and evolve data models across SQL and NoSQL databases, choosing the right store for the job•⁠ ⁠Design secure, scalable REST APIs and auth (JWT, OAuth, RBAC)•⁠ ⁠Mentor other engineers code review, pairing, unblocking, raising the bar on standards•⁠ ⁠Break down complex work into clear, shippable pieces for the team•⁠ ⁠Translate business needs into technical plans and explain trade-offs to non-technical stakeholders•⁠ ⁠Integrate third-party services: payments, notifications, payroll, e-signing/ID verification•⁠ ⁠Lead performance work: query optimisation, caching, cloud deployments, scaling for load•⁠ ⁠Set the standard for how to use AI tooling where it speeds us up, where it doesn't, and how we keep quality high•⁠ ⁠Make build-vs-buy calls and drive technical documentation and standardsWhat we're looking for•⁠ 6 -⁠ 8+ years professional full-stack experience, including leading a team or owning a major system•⁠ ⁠Deep Node.js expertise, ideally with Nest.js, and strong React.js in production•⁠ ⁠Strong TypeScript, modern JavaScript (ES6+), async patterns, API lifecycle, and system design•⁠ ⁠Hands-on with both SQL (PostgreSQL, MySQL) and NoSQL (MongoDB, Redis) including schema design, indexing, and query optimisation•⁠ ⁠Cloud deployment experience (DigitalOcean, AWS, or similar)•⁠ ⁠Fluent with AI coding tools (Claude Code, Copilot, Cursor, or similar) as part of a daily workflow and possessing the judgement to know when to rely on them and when not to. You review AI-generated code as rigorously as human-written code•⁠ ⁠Track record of mentoring engineers and levelling up a team•⁠ ⁠Strong written and verbal communication; comfortable presenting technical decisions to product, leadership, and clients•⁠ ⁠Proven ownership: takes features from concept to production without hand-holding•⁠ ⁠Comfortable in an English-speaking, distributed international teamNice to have: React Native / mobile development, microservices, WebSockets, queues, CI/CD, DOKS, SaaS/startup scaling experience, GDPR familiarity