Protect your APIs and simulate real-world usage limits
What is Rate Limiting?
Rate limiting is a technique to control how many requests a client can make to your API within a specific time window. It prevents abuse, ensures fair usage, and protects server resources.
Why Use Rate Limiting?
Prevent Abuse: Stop malicious users from overwhelming your API
Fair Usage: Ensure all users get equal access to resources
Cost Control: Limit expensive operations and database queries
Real-World Testing: Simulate production API behavior in development
Performance: Maintain consistent response times under load
How It Works
Mock API Builder uses an advanced sliding window algorithm:
1
Request Arrives
Client initiates connection to API endpoint
2
Check Limit
Calculates request count in the current sliding window
3
Decision
Under limit: Allow
Over limit: Block (429)
4
Reset
Window slides forward, reclaiming request quota
Configuration Options
Request Limit
Maximum requests per window
Per minute: 60 requests/min (default)
Per day: 5,000 requests/day (default)
Shared APIs: Higher burst limits apply
Time Window
Duration of request counting
Strict: 1 minute (60s)
Standard: 15 minutes (900s)
Lenient: 1 hour (3600s)
Error Response (429)
When limited, clients receive a 429 Too Many Requests status with standardized headers:
Status
429
Code
TOO_MANY_REQUESTS
Retry After
300s
json
Integration Example
Standard fetch implementation with retry logic:
javascript
Best Practices
Always monitor headers: Watch X-RateLimit-Remaining for pro-active throttling.
Implement Exponential Backoff: Don't just hammer the API after Retry-After expires.
Graceful Degradation: Show users cached data when rate limited.