Expertise
Node.js expertise: APIs and backend services in TypeScript
Node.js is the most widely used server-side JavaScript runtime. Its non-blocking model makes it particularly efficient for high-concurrency APIs, real-time features and service integrations. Recent LTS releases bring native TypeScript support, ES modules, fetch and a built-in test runner.
Agencei uses Node.js with TypeScript for REST and GraphQL APIs, SaaS backends, notification and synchronisation services, serverless functions and automation tools. Our preferred frameworks are NestJS for structured applications and Fastify for lightweight services.
It is the natural choice when your team already masters JavaScript on the frontend, when you want to share types and validation rules between client and server, or when you need to ship fast without sacrificing structure.
Use cases
REST and GraphQL APIs
Structured backends with NestJS or Fastify, Zod schema validation, OpenAPI documentation and JWT or OpenID Connect authentication.
Real-time features
Notifications, chat, position tracking or live dashboards with WebSocket or Server-Sent Events, and Redis for broadcasting across instances.
Backend for Frontend
Aggregation layer between several internal APIs and a web or mobile app, to simplify calls and reduce round trips.
Integrations and webhooks
Receiving and sending webhooks (payment, CRM, ERP), task queues with BullMQ and handling of retries and idempotency.
Serverless functions
Event-driven processing on AWS Lambda: image resizing, data transformation, responses to S3 or SQS events.
Automation tools
Scripts and services that synchronise systems, generate documents or orchestrate calls to AI models.
Project types
- REST or GraphQL API
- SaaS backend
- Real-time service
- Backend for Frontend (BFF)
- AWS Lambda functions
- Integration and webhook service
- Internal automation tool
Integration with the rest of the stack
Node.js + React or Next.js
Types and validation schemas shared in a monorepo; the frontend consumes the API through automatically generated typed clients.
Node.js + PostgreSQL or MongoDB
Prisma or Drizzle for PostgreSQL, Mongoose or the native driver for MongoDB, with versioned migrations and integration tests on a real database.
Node.js + Redis + BullMQ
Caching, sessions, rate limiting and asynchronous task queues to move long-running work out of the request cycle.
Node.js + Docker + Kubernetes or AWS Lambda
Lightweight multi-stage images for long-running services, or Lambda functions bundled with esbuild for event-driven processing.
Examples of problems solved
Blocked event loop
Identifying expensive synchronous operations (large JSON, cryptography, regex) and offloading them to worker threads or a task queue.
Memory leak in a long-running service
Heap snapshot analysis, fixing listeners never removed, unbounded caches and closures that retain objects.
Unhandled promise rejections crashing the process
Introducing centralised error handling, timeouts on outgoing calls and graceful shutdown with connection draining.
Outdated and vulnerable dependencies
npm audit, progressive upgrades, replacement of abandoned packages and version locking in CI.
High latency on an API under load
Profiling, tuning database connection pools, caching stable responses and moving to Fastify when the framework is the bottleneck.
Frequently asked questions
NestJS or Fastify: which one should we choose?
NestJS brings strong structure (modules, dependency injection) suited to teams and growing applications. Fastify is lighter and faster, ideal for focused services. NestJS can also run on top of Fastify.
Is Node.js suitable for CPU-intensive processing?
Not natively: heavy computation blocks the event loop. In that case we use worker threads, a task queue, or delegate the processing to a Java or Python service.
Do you use TypeScript on the server side?
Yes, always. Strict typing, schemas shared with the frontend and API client generation significantly reduce production errors.
How do you secure a Node.js API?
Validation of every input, signed-token authentication, security headers, rate limiting, secrets kept out of the code and dependency scanning in CI.
Which Node.js version do you use?
The active LTS release at the time of the project, to benefit from security fixes over several years. We plan version upgrades before support ends.
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