API Rate Limiting Blueprint

Design a rate limiting strategy for our {{api_type}} API. Requirements:

User base: {{user_profile}}
Traffic: {{traffic_characteristics}}
Business model: {{pricing_tier}}

Provide: (1) algorithm choice (token bucket, sliding window, etc.) with rationale, (2) quota structure per tier, (3) Redis/in-memory implementation sketch, (4) response headers and error responses, (5) burst handling and grace period policy.