Senior Node.JS Developer

Role summary 

As Senior Node Engineer You partner with the engagement Tech Lead on architecture, you set the bar on code quality, you mentor mid-level engineers as the squad grows, and you take direct ownership of the gateway service after the knowledge-transfer period closes. 

What you'll do 

First 90 days 

• Read and document the existing BFF codebase alongside the outgoing engineering team 
• Produce a quality baseline: test coverage, TypeScript strictness, lint compliance, dependency freshness, CI duration, flake rate 
• Lead the knowledge-transfer sessions for the BFF service from the client's team 
• Identify the highest-risk subsystems and propose stabilisation plans 
• Set the squad's code-review standards, branching model, and definition of done 

Ongoing 

• Own architecture decisions for the BFF service 
• Lead design reviews for new endpoints, especially the AI integration surface 
• Pair with mid-level engineers and review their work 
• Represent the BFF squad in cross-team architecture discussions 
• Participate in on-call rotation once we take production ownership 

We are partnering with a US-based health-tech company on the takeover of a production AI-powered mobile coaching platform. The platform serves real users today via iOS + Android apps and a microservices backend on AWS. You will join the Polish team responsible for the platform's Backend-for-Frontend (BFF) and supporting Node services as they transition from the original engineering team to ours. 

Must-have skills 

• 5+ years Node.js in production, 3+ years NestJS 
• Strong TypeScript — strict mode, generics, type narrowing, no any-as-escape-hatch 
• NestJS depth: modules, providers, DI scope, guards, interceptors, pipes, custom decorators 
• REST API design at scale; familiarity with BFF / API-gateway patterns 
• GraphQL or schema federation comfort (not required to be primary stack) 
• MongoDB in production — Mongoose or native driver, schema design, indexing 
• Auth0 integration — both user authentication flows and Machine-to-Machine (M2M) client credentials 
• AWS production experience — ECS or EKS, IAM, VPC, RDS, ElastiCache 
• CI/CD on GitHub Actions 
• Distributed tracing and structured logging in production environments 
• Comfortable writing tests (Jest) and raising coverage on legacy code