Freelance Senior Fullstack Developer (AWS Serverless)

The Role

For a large-scale HR transformation program, we are looking for a Senior Full Stack Developer to help build a modern HR Connector platform on AWS.

The goal: replace complex point-to-point integrations with a scalable, event-driven integration layer connecting multiple HR systems (Payroll, ATS, LMS, etc.).

You will join a fast-paced Scrum team working under tight deadlines with high business impact.

Responsibilities

• Design and build robust, scalable integrations between HR systems
• Translate business needs into technical solutions
• Take end-to-end ownership (analysis → development → testing → delivery)
• Develop:
• Backend logic & APIs
• Event-driven workflows
• Integration flows
• Frontend components when needed
• Ensure high-quality delivery through:
• Unit testing & API testing
• End-to-end validation

Tech Stack

• Node.js (v22), TypeScript
• AWS Serverless: Lambda, API Gateway, EventBridge, Step Functions, SQS, S3
• Infrastructure: Terraform, GitLab CI/CD
• Data: PostgreSQL / Aurora Serverless, Athena, Glue
• Testing: Vitest, Cucumber, Gherkin
• Monitoring: CloudWatch, Dynatrace

Profile

• Proven experience as Senior Full Stack or Backend Developer
• Strong experience with:
• Node.js & TypeScript
• AWS (serverless)
• System integrations / APIs
• Event-driven architectures
• Comfortable working on complex data flows
• Experience with Terraform / IaC is a strong plus
• Strong ownership & delivery focus
• Pragmatic, hands-on problem solver
• Quality-driven (TDD, maintainability, performance awareness)
• Able to thrive in a high-pressure delivery environment

Languages

• Fluent in Dutch and English