LLDHub
Problems·Rate Limiter
L7 · Hard

Rate Limiter

Problem

Design a rate limiting service that restricts request rates per user/IP using multiple algorithms.

Requirements

  • Support algorithms: Fixed Window, Sliding Window, Token Bucket, Leaky Bucket
  • Configure limits per user, per API endpoint, or globally
  • Return remaining quota and reset time in headers
  • Distributed rate limiting (multiple server nodes)
  • Allow burst allowance with token bucket

Constraints

  • Precision: milliseconds
  • Redis for distributed state
  • Config: max_requests, window_size per rule
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