docs/python-sdk/fastmcp-server-middleware-rate_limiting.mdx

---
title: rate_limiting
sidebarTitle: rate_limiting
---

# `fastmcp.server.middleware.rate_limiting`


Rate limiting middleware for protecting FastMCP servers from abuse.

## Classes

### `RateLimitError` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/rate_limiting.py#L15"><Icon icon="github" size="14" /></a></sup>


Error raised when rate limit is exceeded.


### `TokenBucketRateLimiter` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/rate_limiting.py#L22"><Icon icon="github" size="14" /></a></sup>


Token bucket implementation for rate limiting.


### `SlidingWindowRateLimiter` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/rate_limiting.py#L61"><Icon icon="github" size="14" /></a></sup>


Sliding window rate limiter implementation.


### `RateLimitingMiddleware` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/rate_limiting.py#L92"><Icon icon="github" size="14" /></a></sup>


Middleware that implements rate limiting to prevent server abuse.

Uses a token bucket algorithm by default, allowing for burst traffic
while maintaining a sustainable long-term rate.


### `SlidingWindowRateLimitingMiddleware` <sup><a href="https://github.com/jlowin/fastmcp/blob/main/src/fastmcp/server/middleware/rate_limiting.py#L170"><Icon icon="github" size="14" /></a></sup>


Middleware that implements sliding window rate limiting.

Uses a sliding window approach which provides more precise rate limiting
but uses more memory to track individual request timestamps.