Distributed Rate Limiter

Implemented sophisticated rate limiting supporting multiple algorithms: token bucket, sliding window, and leaky bucket. Uses Redis for distributed coordination across service instances to enforce global rate limits. Handles complex scenarios like burst capacity, per-user limits, and time-based quota resets. Achieves microsecond response times with minimal overhead through careful algorithm design and caching strategies.

The system supports hierarchical limits—global, per-tenant, and per-endpoint. Redis scripts ensure atomic operations without race conditions. Metrics are exposed for monitoring, showing current usage, rejections, and quota utilization to help identify bottlenecks.