Node.js Development Company

Express is still the most widely known Node framework, and it is also the least structured: routing, validation, error handling and dependency wiring are all left to whatever convention the original developer chose, which becomes a liability once more than one or two engineers touch the codebase.

NestJS solves that by imposing structure similar to Angular's: modules, decorators, dependency injection and a clear place for everything. It costs more boilerplate upfront and pays back on any service with real business logic and a team of more than one or two developers. Fastify sits in between: it is faster than Express and has a plugin architecture, but it does not impose NestJS's full architectural opinions, so we reach for it when raw throughput matters and the service is simple enough not to need NestJS's structure.

Node's event loop is single-threaded, so a CPU-heavy operation (resizing a large image, parsing a huge CSV, running a complex calculation) blocks every other request on that process while it runs. This is the most common performance mistake we see in Node codebases: a synchronous, expensive operation dropped directly into a request handler.

The fix is usually one of two paths. Worker threads move the CPU-bound work to a separate thread within the same Node process, appropriate for occasional, moderate-weight tasks. A dedicated background job queue (BullMQ, backed by Redis) moves the work out of the request-response cycle entirely, appropriate for anything that does not need to finish before the client gets a response. For workloads that are CPU-bound as their primary characteristic, such as a service that does nothing but transform large datasets, we typically recommend building that specific service in Go or another language better suited to raw computation, and keeping Node for the I/O-bound API layer around it.