---
title: Rate Limiting
description: Enforce rate limits from a worker with the Rate Limiting binding.
sidebar:
  badge: Experimental
---

The [Rate Limiting binding](https://developers.cloudflare.com/workers/runtime-apis/bindings/rate-limit/) lets a worker check and increment a rate limit counter. The `exp/cloudflare/ratelimit` package wraps it.

:::warning[Experimental]
This package lives under `exp/cloudflare` and its API may change.
:::

## Declare the binding

```toml
[[ratelimits]]
name = "MY_RATE_LIMITER"
namespace_id = "1001"
simple = { limit = 100, period = 60 }
```

`namespace_id` identifies the counter namespace — bindings that share it, even across different workers, share counters for a given key. `simple.period` must be `10` or `60` seconds.

## Check a key

`ratelimit.NewRateLimit` resolves the binding by name. `Limit` increments the counter for `RateLimitOptions.Key` and returns a `RateLimitOutcome` whose `Success` field reports whether the key is under the limit.

```go
import (
	"net/http"

	"github.com/syumai/workers-go"
	"github.com/syumai/workers-go/exp/cloudflare/ratelimit"
)

func main() {
	workers.Serve(http.HandlerFunc(func(w http.ResponseWriter, req *http.Request) {
		rl, err := ratelimit.NewRateLimit("MY_RATE_LIMITER")
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		outcome, err := rl.Limit(ratelimit.RateLimitOptions{
			Key: req.RemoteAddr,
		})
		if err != nil {
			http.Error(w, err.Error(), http.StatusInternalServerError)
			return
		}
		if !outcome.Success {
			http.Error(w, "rate limit exceeded", http.StatusTooManyRequests)
			return
		}
		w.Write([]byte("ok"))
	}))
}
```