fasthttp — High-Performance HTTP Server Library for Go

Introduction

fasthttp is a Go HTTP library designed from scratch for high throughput and low memory allocation. Unlike the standard net/http package, it reuses request and response objects via object pooling, making it a strong choice for proxy servers, API gateways, and any service that handles tens of thousands of concurrent connections.

What fasthttp Does

• Provides a zero-allocation HTTP server and client for Go
• Reuses request/response objects with sync.Pool to reduce GC pressure
• Supports HTTP/1.1 pipelining and keep-alive connections by default
• Offers a RequestCtx-based API for handling requests without per-request heap allocation
• Includes built-in helpers for common tasks like file serving, routing, and compression

Architecture Overview

fasthttp avoids the net/http pattern of creating a new goroutine with fresh allocations per request. Instead, it maintains a worker pool and recycles RequestCtx objects. Buffers for headers, URI parsing, and body reading are pre-allocated and grown only when needed. This design trades API familiarity for raw throughput, making it measurably faster under sustained load while using less memory.

Self-Hosting & Configuration

• Install via go get github.com/valyala/fasthttp with Go 1.20+
• Configure concurrency limits with Server.Concurrency to cap worker goroutines
• Set Server.ReadTimeout and Server.WriteTimeout for connection lifecycle control
• Enable TLS by passing cert and key files to ListenAndServeTLS
• Use Server.MaxRequestBodySize to guard against oversized payloads

Key Features

• Up to 10x lower memory allocation per request compared to net/http
• Built-in connection pooling for the HTTP client
• Streaming request and response body support
• Hot path optimizations for header parsing and URI decoding
• Compatible with popular routers like fasthttp/router and fiber

Comparison with Similar Tools

• net/http — standard library, broader ecosystem, but higher allocation per request
• Fiber — web framework built on top of fasthttp with Express-like API
• Echo — net/http-based framework with middleware, slightly lower raw throughput
• Gin — net/http-based, strong middleware ecosystem, simpler migration from net/http

FAQ

Q: Can I use fasthttp as a drop-in replacement for net/http? A: No. The API differs significantly — fasthttp uses RequestCtx instead of http.Request/http.ResponseWriter. Migration requires rewriting handlers.

Q: Does fasthttp support HTTP/2? A: Not natively. For HTTP/2 you need net/http or a reverse proxy like Nginx in front.

Q: When should I stick with net/http? A: If your service is I/O-bound rather than CPU-bound, or if you rely heavily on net/http middleware, the standard library is the simpler choice.

Q: Is fasthttp production-ready? A: Yes. It has been used in production at scale for years and is the engine behind the Fiber framework.

Sources

• https://github.com/valyala/fasthttp
• https://pkg.go.dev/github.com/valyala/fasthttp