Automating API Regression and Rate Limit Tests with Sequential Runners
How to use automated sequential request loops to stress-test rate limits, verify idempotency, and detect intermittent API regressions in web applications.
Why Run Sequential API Tests?
Testing an endpoint once verifies that it works under optimal conditions. But how does it behave when called 20 times in a row? Does your token bucket rate limiter return HTTP 429 Too Many Requests with a proper Retry-After header? Does creating an item multiple times lead to duplicate database entries or properly honor idempotency keys?
Key Scenarios for Batch and Sequential Testing
- Rate Limit Verification: Dispatch rapid calls with low delays (200ms) to ensure your API gateway or Cloudflare rules enforce throttling accurately.
- Polling and Webhook Verification: Schedule repeated calls with 2-second or 5-second delays to inspect status updates while background workers process asynchronous jobs.
- Intermittent Latency Detection: Measure jitter across 10-30 iterations to identify cold start delays in serverless functions (like AWS Lambda, Cloudflare Workers, or Vercel Edge).
Using Apier's Auto Runner Safely
Apier gives you full control over run count (up to 50 iterations) and delay parameters (200ms to 10 seconds), plus an immediate cancel button. During the run, you can watch the iteration count, percent completion, and response codes update live without locking the browser tab.