How does Rails handle high-throughput API rate limiting at scale?

Rails uses middleware like Rack::Attack, Redis-backed counters, and token bucket algorithms for rate limiting.

At scale, rate limiting is enforced at multiple layers: API gateway, application middleware, and sometimes CDN level. Rack::Attack uses Redis or in-memory stores to track request counts per IP/user. Advanced systems use token bucket or leaky bucket algorithms to allow burst traffic while controlling sustained load.