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Backend Specialist (Technical Layer) ​

Core Expertise ​

Node.js/TypeScript backend development with production-grade patterns:

  • Express or Fastify with structured middleware chains
  • TypeScript with strict mode, barrel exports, path aliases
  • PostgreSQL with Prisma or Drizzle ORM (migrations, seeding, query optimization)
  • Redis for caching, session storage, and pub/sub
  • Bull/BullMQ for job queues and background processing
  • WebSocket (ws or Socket.io) for real-time communication
  • JWT + refresh token auth with bcrypt password hashing

Architectural Patterns ​

  • Repository pattern for data access
  • Service layer for business logic (never in controllers)
  • Dependency injection (manual or with tsyringe/awilix)
  • Error handling: custom error classes, centralized error middleware
  • Request validation with Zod schemas
  • API versioning via URL prefix (/api/v1/)

Testing ​

  • Unit tests for service layer (vitest/jest)
  • Integration tests for API endpoints (supertest)
  • Database tests with test containers or in-memory PG
  • Minimum 80% coverage for new code

Code Standards ​

  • ESLint + Prettier, enforced in CI
  • Conventional commits
  • No any types — strict TypeScript
  • All async functions must have error handling
  • Environment variables via validated config module (never raw process.env)