Node.js Developer Hiring Checklist for Scalable Back Ends
Node.js is perfect for APIs and real-time products — when it is built by someone who understands async code, errors and production. Use this checklist.
To hire a Node.js developer who can build scalable back ends, check five areas: async programming and error handling, API design, data modelling, security and production operations. Candidates who are strong in all five will build services that keep working when traffic grows.
The checklist
1. Async fundamentals
- Explains the event loop clearly.
- Uses async/await correctly and handles rejected promises.
- Knows how to avoid blocking the event loop with CPU-heavy work.
2. API design
- Designs consistent REST or GraphQL APIs with versioning.
- Validates input with a schema library such as Zod or class-validator.
- Returns meaningful errors and status codes.
3. Data and persistence
- Comfortable with PostgreSQL or MongoDB and an ORM such as Prisma or TypeORM.
- Understands transactions, indexes and migrations.
- Uses Redis for caching or queues when appropriate.
4. Security
- Implements authentication with OAuth2 or JWT safely.
- Applies rate limiting, input sanitisation and secrets management.
- Keeps dependencies updated and audits them.
5. Production readiness
- Writes structured logs and adds health checks.
- Has deployed with Docker, serverless or Kubernetes.
- Knows how to profile memory leaks and slow endpoints.
Framework choice: Express, NestJS or Fastify?
Express is minimal and flexible. NestJS adds structure, dependency injection and modules — useful for larger teams. Fastify focuses on performance. A good developer explains why they would choose one for your project rather than defaulting to habit.
Practical assessment idea
Ask for a small service: an endpoint that accepts a webhook, validates the payload, stores it and processes it in a background job with retries. Include a test. This covers async handling, validation, persistence and resilience in a few hours.
Questions to ask
- How do you handle a third-party API that times out intermittently?
- What happens if two requests update the same record at once?
- How would you add real-time notifications to an existing API?
Build the right pairing
A Node.js developer often pairs with a React developer for full-stack JavaScript teams, and a DevOps engineer once traffic and infrastructure grow. Browse our Node.js developers to see vetted profiles.
