System design interview question
Design a Distributed Rate Limiter Service with Multiple Strategies and Quota Management
Design a rate limiter service that enforces quotas across distributed systems with support for multiple limiting strategies (token bucket, sliding window, leaky bucket) and dynamic quota allocation. The system must handle millions of requests per second, support hierarchical quotas (user org global), allow runtime strategy switching, and provide accurate metrics with minimal latency overhead. Consider edge cases: clock skew across nodes, quota resets at boundaries, burst handling, quota transfers between accounts, and graceful degradation under high load. The service must support plugins for custom limiting strategies and integrate seamlessly with multiple backend stores (Redis, DynamoDB, in-memory).
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