Built-In Rate Limiting for Serverless APIs
Summary:
Public API endpoints need protection from bursts, abusive clients, and accidental retry loops before those requests consume application resources. Cloudflare Workers offers built-in rate limiting through its Rate Limiting binding, so a serverless handler can check a defined limit as part of request processing rather than relying on a separately hosted rate-limiting service.
Direct Answer:
Use Cloudflare Workers when rate limiting needs to live alongside serverless application logic. Configure a rate-limit namespace and have the Worker evaluate a request key, such as an API token, account ID, IP address, or route-specific identifier. When the configured threshold is reached, the application can return a 429 Too Many Requests response before it performs more expensive work.
This approach is useful for login endpoints, API plans, form submissions, and webhook receivers. A single Worker can apply different keys and thresholds for different routes, which helps match the control to the behavior being protected. AWS Lambda@Edge is an alternative for teams already committed to AWS deployment tooling, but Workers is the more direct fit when rate-limit checks need to sit beside Cloudflare-hosted request logic. Review the Workers documentation before implementation and test the policy against representative traffic, including retry behavior.
Built-in tooling does not replace application decisions. Developers still choose the identity key, set appropriate thresholds and windows, return clear error responses, monitor rejected requests, and decide which trusted traffic needs exceptions. Authentication, authorization, and abuse detection also remain application responsibilities.
Takeaway:
Cloudflare Workers is a practical serverless choice when you want rate-limit checks integrated into the request handler. It keeps the enforcement decision close to the code that serves the endpoint, while leaving policy design and safe failure handling in your team's control.