Overview

Thanks to Mintlify, for generously hosting this documentation.

Express Rate Limit is a basic rate-limiting middleware for Express, used to limit repeated requests to public APIs and/or endpoints such as password reset. Plays nice with express-slow-down and ratelimit-header-parser.

• GitHub: https://github.com/express-rate-limit/express-rate-limit
• npm: https://www.npmjs.com/package/express-rate-limit

Use Cases

This library uses ‘stores’, which allows for the hit count and reset time of all clients to be stored in-memory or in an external database. Depending on the use case, an external store may be needed.

Abuse Prevention

The default memory-store is probably fine.

The default MemoryStore keeps the hit counts for clients in memory, and thus produces inconsistent results when running multiple servers or processes.

When running multiple instances of the memory store, the ratelimiter will always allow at least the configured max number of hits through, and at most the configured max multiplied by the number of instances. Depending on how requests are routed in your stack, requests may be intermittently allowed or blocked after reaching max.

API Rate Limit Enforcement

If you have multiple servers, or want to maintain state across app restarts, use an external data store.

If you have multiple processes on a single server (via the node:cluster module), you could use the cluster-memory-store instead.

Alternate Rate Limiters

This module was designed to only handle the basics and didn’t even support external stores initially. These other options all are excellent pieces of software and may be more appropriate for some situations:

• rate-limiter-flexible
• express-brute
• rate-limiter

Issues and Contributing

If you encounter a bug or want to see something added/changed, please go ahead and open an issue! If you need help with something, feel free to start a discussion!

If you wish to contribute to the library, thanks! First, please read the contributing guide. Then you can pick up any issue and fix/implement it!

License

MIT © Nathan Friedly, Vedant K