upstash / ratelimit-js

The library is designed for places a stateful Redis connection does not fit: Lambda and other serverless functions, Vercel Edge, Cloudflare Workers and Pages, Fastly Compute@Edge, and client-side or WebAssembly code. Its own README calls it the only connectionless rate limiter of its kind, and describes the project as in GA with ongoing Upstash support. Usage is a few lines: construct a Ratelimit with a chosen algorithm such as slidingWindow, then call .limit(identifier) per request and branch on the returned success.

The skill itself is deliberately thin: its own description calls it "lightweight guidance" — setup and basic usage, with pointers onward to Upstash's own docs for the deeper algorithm choices, feature list, pricing, and traffic-protection material rather than reproducing all of that inside the skill. It is for teams already on, or willing to adopt, Upstash Redis who need rate limiting at the edge or in a serverless function; it buys nothing if you are not using Upstash Redis, since the whole design depends on that specific hosted REST API.

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Checked from the package's own README and skill description; we have not run the SDK against a live Upstash database ourselves.