Full Stack Developer

We’re looking for a hands-on Full-Stack Developer to build and scale the internal tools and AI-powered applications that support Merkle’s delivery. You’ll own the application layer end-to-end - from the backend up through the frontend - covering backend logic, infrastructure, authentication, deployments, and day-to-day stability.

• Location: Rotterdam
• Full time
• Fixed Term Contract (Fixed Term)

What You’ll Do

• Own and maintain the full application stack across our internal tools: backend, database, auth, and frontend
• Design and implement authentication and access control (e.g., SSO with SAML or Okta, multi-tenant data isolation, role-based access)
• Write and maintain database schemas, migrations, and access policies (e.g., PostgreSQL with RLS and RPC functions)
• Build and manage serverless backend functions (e.g., for application logic and API integrations)
• Set up and maintain CI/CD pipelines and manage deployments across environments (e.g., DEV, UAT, PROD)
• Build and maintain modern frontends (e.g., React, Vite, TypeScript)
• Debug and resolve issues across the stack (e.g., build errors, networking, misconfigured services, 5xx errors)
• Collaborate with the AI/LLM side of the team to integrate model outputs cleanly into the application
• Take ownership from idea → build → run → improve

What You Bring

• 3+ years in software engineering (full-stack, AI, or platform development)
• Experience with modern JavaScript/TypeScript stacks (React, Next.js, Node.js), frontend and backend
• Experience with Docker and self-hosted infrastructure, not just managed cloud services
• Knowledge and experience with multi-tenant application patterns
• Solid problem-solving skills and strong ownership mindset

Strong advantage:

• Familiarity with backend-as-a-service platforms (e.g., Supabase, Firebase) for auth, database, storage, and serverless functions
• Exposure to alternative JS/TS runtimes (e.g., Deno, Bun)

Nice to Have

• Hands-on experience with LLM APIs (e.g., OpenAI, Anthropic)
• Familiarity with SSE streaming or real-time data patterns
• Familiarity with MarTech platforms (e.g., Adobe, Salesforce, CDPs)
• Experience with authentication systems (e.g., OAuth2, SAML, SSO)

Why This Role

• Build products, not projects
• Direct impact on how Merkle delivers at scale
• Work at the intersection of AI, engineering, and platform thinking
• High ownership and room to shape solutions

What We Offer

• A dynamic, international work environment with colleagues from around the globe.
• A challenging position at a successful company in a growing market.
• A fun and inclusive culture-think foosball, table tennis, themed events, and team parties.
• 3 extra days off (yes, at Merkle we take your well-being very seriously) - in addition to 25 annual vacation days, there are 3 Well-being Days.
• 2 Social Impact Days - you can volunteer for a charity of your choice.
• Extensive learning and development opportunities, including a wide range of personal and online training.
• A hybrid work model, with 2-3 days in the office and the rest working from home.
• A competitive salary and excellent secondary benefits.

Company Description

Merkle, a dentsu company, operates in 30+ countries with over 16,000 employees. In the Netherlands, more than 150 Merkle employees work with clients like ASML, Albert Heijn, HEMA, Carglass, and Signify. Merkle Netherlands is a strategic partner of Google, Adobe, Salesforce, and Selligent.