Question 1

How does FastAPI-Limiter compare to slowapi for rate limiting?

Accepted Answer

FastAPI-Limiter is specifically designed for FastAPI with better dependency injection integration and WebSocket support, while slowapi is more general-purpose but might offer more backends. FastAPI-Limiter uses pyrate-limiter, whereas slowapi has different storage options, so choice depends on your need for FastAPI-specific features.

Question 2

How to skip rate limiting for certain endpoints in FastAPI-Limiter?

Accepted Answer

Use the skip callable parameter in RateLimiter, as shown in the README, where you define an async function that returns True to skip based on conditions like request path or user roles. This allows fine-grained control without modifying global settings.

Question 3

Can FastAPI-Limiter handle rate limiting with Redis for distributed setups?

Accepted Answer

The library does not natively support Redis or other persistent storage; it relies on pyrate-limiter which is in-memory by default. For distributed applications, you may need to extend pyrate-limiter or consider alternative solutions with built-in distributed support.

Question 4

How to set up global rate limiting for all routes using FastAPI-Limiter?

Accepted Answer

Add RateLimiterMiddleware to your FastAPI app with app.add_middleware(RateLimiterMiddleware, limiter=...), as demonstrated in the middleware example. This applies rate limits globally without adding dependencies to each route individually.

Question 5

What happens when a rate limit is exceeded in FastAPI-Limiter?

Accepted Answer

By default, it raises an HTTPException with a 429 status code, but you can customize this with a callback function to implement different responses, such as logging or returning a custom error message, as shown in the callback section.

Question 6

How to rate limit WebSocket messages in FastAPI with this library?

Accepted Answer

Use WebSocketRateLimiter within the websocket handler, as shown in the example where ratelimit is called with context_key for each message. This allows rate limiting based on data sent over the socket, not just connection attempts.

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