Rack::Attack is a Rack middleware for blocking and throttling abusive requests.
The tool addresses the problem of protecting web applications from malicious or misbehaving clients by providing a declarative way to define rules that allow, block, or throttle requests based on their properties. It works by intercepting requests at the middleware level and evaluating them against configured rules before they reach the application. Safelists take precedence and permit requests that match their criteria regardless of other rules, while blocklists and throttles can restrict access based on IP addresses, subnets, or custom conditions.
Developers should choose this tool when they need straightforward request filtering without building custom protection logic. It suits Rails and Rack applications of any size that face abuse from specific clients or need rate limiting. The tool provides built-in methods for IP-based safelisting and blocklisting, custom safelisting via blocks, throttling with configurable limits, and Fail2Ban-style progressive blocking. It also supports RateLimit headers for compliant clients and integrates with Rails applications by default while remaining optional for other Rack-based projects.
The project's issue tracker shows that community engagement centers on questions, feature requests, and middleware-related discussions, indicating active user interest in extending and understanding the tool's capabilities.
