Introducing a Rate Limiter Library for Go

#go #webdev #programming #opensource

In modern backend systems, rate limiting is essential.

Without it, APIs are exposed to abuse, resource exhaustion, and unfair usage.

That’s why I built a production-ready, thread-safe rate limiter library in Go, based on the Token Bucket algorithm.

Why Token Bucket?

I chose the Token Bucket algorithm because it:

Allows controlled bursts of traffic
Provides smooth request flow
Is widely used in production systems
Is simple to understand and reason about

Each client gets a bucket of tokens that refills over time.

Requests consume tokens — once the bucket is empty, requests are rejected.

Library Highlights

This library focuses on correctness and simplicity:

Production-ready & thread-safe
Token Bucket algorithm with burst support
Fast in-memory storage
Detailed rate limit results (remaining, retry-after, reset time)
Extensive unit tests and race-condition testing
Optional cleanup for stale entries

Quick Example

config := limiter.Config{
    Rate:     10,
    Duration: time.Second,
    Burst:    20,
}

store := store.NewMemoryStore(5 * time.Minute)
rateLimiter, _ := limiter.NewTokenBucket(config, store)

if rateLimiter.Allow("user123") {
    fmt.Println("Request allowed")
}