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

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 standards

What 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
• 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 team

Nice to have:

• React Native / mobile development
• microservices
• WebSockets
• queues
• CI/CD
• DOKS
• SaaS/startup scaling experience
• GDPR familiarity