\n\n> **📢 This is a fork of [express-rate-limit](https://github.com/express-rate-limit/express-rate-limit) with additional fixes and improvements.**\n\nBasic rate-limiting middleware for [Express](http://expressjs.com/). Use to\nlimit repeated requests to public APIs and/or endpoints such as password reset.\n\n## 🔧 Changes in this fork\n\nThis fork includes the following improvements over the original package:\n\n- ✅ **Fixed `ipv6Subnet` validation range** – Now supports values from `1` to `120` (was limited to `32-64`), allowing more flexible IPv6 subnet configurations.\n- ✅ **Added `levenshteinDistance` for smart suggestions** – When you mistype an option (e.g., `windowMS` instead of `windowMs`), the error message now suggests the correct option.\n- ✅ **Improved `knownOptions` validation** – Uses Levenshtein distance to suggest the closest valid option when an unknown option is provided.\n- ✅ **Fixed `creationStack` validation** – Removed the conditional `localKeys` check, so the validation always throws an error when the rate limiter is created inside a request handler (preventing memory leaks).\n- ✅ **Added `windowMs` validation in `parseOptions`** – Validates `windowMs` during configuration parsing for MemoryStore, catching errors earlier.\n- ✅ **Fixed `RateLimit-Reset` header in `setDraft6Headers`** – Now the header is only set when the store actually provides a `resetTime`, as per the draft-6 specification.\n- ✅ **Exported `rawValidations`** – Allows advanced testing with validations that throw errors directly (without wrapping in try/catch).\n\n## Usage\n\n```ts\nimport { rateLimit } from '@bozorgwar/express-rate-limit'\n\nconst limiter = rateLimit({\n\twindowMs: 15 * 60 * 1000, // 15 minutes\n\tlimit: 100, // Limit each IP to 100 requests per `window` (here, per 15 minutes).\n\tstandardHeaders: 'draft-8',\n\tlegacyHeaders: false,\n\tipv6Subnet: 56, // Now supports any value between 1 and 120!\n})\n\napp.use(limiter)\nInstallation\nbash\nnpm install @bozorgwar/express-rate-limit\nData Stores\nThe rate limiter comes with a built-in memory store, and supports a variety of\nexternal data stores.\n\nConfiguration\nAll function options may be async. Click the name for additional info and\ndefault values.\n\nOption\tType\tRemarks\n[`windowMs`]\tnumber\tHow long to remember requests for, in milliseconds.\n[`limit`]\tnumber | function\tHow many requests to allow.\n[`message`]\tstring | json | function\tResponse to return after limit is reached.\n[`statusCode`]\tnumber\tHTTP status code after limit is reached (default is 429).\n[`handler`]\tfunction\tFunction to run after limit is reached (overrides message and statusCode settings, if set).\n[`legacyHeaders`]\tboolean\tEnable the X-Rate-Limit header.\n[`standardHeaders`]\t'draft-6' | 'draft-7' | 'draft-8'\tEnable the Ratelimit header.\n[`identifier`]\tstring | function\tName associated with the quota policy enforced by this rate limiter.\n[`store`]\tStore\tUse a custom store to share hit counts across multiple nodes.\n[`passOnStoreError`]\tboolean\tAllow (true) or block (false, default) traffic if the store becomes unavailable.\n[`keyGenerator`]\tfunction\tIdentify users (defaults to IP address).\n[`ipv6Subnet`]\tnumber (1-120) | function | false\tHow many bits of IPv6 addresses to use in default keyGenerator (now supports 1-120!)\n[`requestPropertyName`]\tstring\tAdd rate limit info to the req object.\n[`skip`]\tfunction\tReturn true to bypass the limiter for the given request.\n[`skipSuccessfulRequests`]\tboolean\tUncount 1xx/2xx/3xx responses.\n[`skipFailedRequests`]\tboolean\tUncount 4xx/5xx responses.\n[`requestWasSuccessful`]\tfunction\tUsed by skipSuccessfulRequests and skipFailedRequests.\n[`validate`]\tboolean | object\tEnable or disable built-in validation checks.\n[`logger`]\tLogger\tCustom logger\nIssues and Contributing\nIf you encounter a bug or want to see something added/changed, please go ahead\nand open an issue!\nIf you need help with something, feel free to\nstart a discussion!\n\nThank You\nThanks to the original authors (Nathan Friedly, Vedant K) for creating this excellent package, and to Mintlify for hosting the documentation at\nexpress-rate-limit.mintlify.app\n\n
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