Fiber — Overview#

Identity#

  • Module path: github.com/gofiber/fiber/v3
  • Go version: 1.25.0
  • License: MIT (Copyright 2019-present Fenny and Contributors)
  • Repository: https://github.com/gofiber/fiber

Purpose#

Fiber is an Express.js-inspired web framework for Go built on top of fasthttp — the fastest HTTP engine in the Go ecosystem. It targets Go developers who want a familiar, ergonomic API (borrowed from Node.js/Express) without sacrificing Go’s raw performance. The framework is designed for fast development with zero memory allocation and high throughput in mind.

Significance#

Fiber is one of the most starred Go web frameworks on GitHub (35k+ stars as of 2025), widely adopted by developers migrating from Node.js and by teams optimizing for high-performance HTTP services. Its fasthttp foundation makes it a performance benchmark reference point in the Go ecosystem. The v3 release (current) represents a mature, breaking-change redesign with improved type safety (generated Ctx/Req/Res interfaces), a built-in HTTP client, and a growing middleware ecosystem.

Key metrics#

  • Go files: 243 (51 at root, rest in subdirectories)
  • Top-level directories: addon, binder, client, docs, extractors, internal, log, middleware (30+ sub-packages)
  • Direct dependencies: 11 (fasthttp, gofiber/schema, gofiber/utils/v2, google/uuid, mattn/go-colorable, mattn/go-isatty, shamaton/msgpack/v3, stretchr/testify, tinylib/msgp, valyala/bytebufferpool, golang.org/x/crypto)
  • go.sum entries: ~49 lines (~24 total modules including indirect)
  • Current version: v3.1.0

Notable characteristics#

  • fasthttp foundation, not net/http: Fiber deliberately avoids the standard net/http package, using valyala/fasthttp instead. This means zero-allocation request handling and significantly higher raw throughput, but also incompatibility with net/http middleware ecosystems (hence the adaptor middleware to bridge the gap).
  • Generated interface layer: ctx_interface_gen.go, req_interface_gen.go, and res_interface_gen.go are machine-generated via ifacemaker, providing stable, typed interfaces (Ctx, Req, Res) over the concrete implementations. This enables test mocking and clean separation without hand-maintaining boilerplate.
  • Batteries-included middleware suite: The middleware/ directory ships ~30 production-ready middleware packages (CORS, CSRF, rate limiting, sessions, caching, auth, compression, logging, health checks, etc.) directly in the core repository, reducing the need for third-party additions.
  • Built-in HTTP client: The client/ package provides a full-featured HTTP client alongside the server framework, sharing serialization and configuration infrastructure — unusual for a framework to bundle both sides.
  • Prefork support: prefork.go implements UNIX SO_REUSEPORT-based multi-process serving, allowing Fiber to utilize multiple CPU cores at the OS level without Go’s GC coordination overhead across processes.
Backward Echo — Testing Fiber — Structure Forward