> ## Documentation Index
> Fetch the complete documentation index at: https://gofastmcp.com/llms.txt
> Use this file to discover all available pages before exploring further.
# rate_limiting
# `fastmcp.server.middleware.rate_limiting`
Rate limiting middleware for protecting FastMCP servers from abuse.
## Classes
### `RateLimitError`
Error raised when rate limit is exceeded.
### `TokenBucketRateLimiter`
Token bucket implementation for rate limiting.
**Methods:**
#### `consume`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
consume(self, tokens: int = 1) -> bool
```
Try to consume tokens from the bucket.
**Args:**
* `tokens`: Number of tokens to consume
**Returns:**
* True if tokens were available and consumed, False otherwise
### `SlidingWindowRateLimiter`
Sliding window rate limiter implementation.
**Methods:**
#### `is_allowed`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
is_allowed(self) -> bool
```
Check if a request is allowed.
### `RateLimitingMiddleware`
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.
**Methods:**
#### `on_request`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any
```
Apply rate limiting to requests.
### `SlidingWindowRateLimitingMiddleware`
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.
**Methods:**
#### `on_request`
```python theme={"theme":{"light":"snazzy-light","dark":"dark-plus"}}
on_request(self, context: MiddlewareContext, call_next: CallNext) -> Any
```
Apply sliding window rate limiting to requests.