Web Dev Helpers
API Response Time Tester
Time a URL from your browser - total, DNS, TCP, TLS, request and response phases.
Request
Your browser: real user timing from your machine. Requires the target server to send CORS headers, andTiming-Allow-Originfor phase breakdown. · Our server: times from our data center (Europe) to the target. Works for any public URL. 100 runs per browser per day.
About this tool
Measure how fast an API endpoint responds from your network. Sends one or more requests (GET or HEAD), captures total latency and reports min/avg/max plus per-phase timings from the Resource Timing API. Cross-origin requests need CORS on the target server, and per-phase timings need Timing-Allow-Origin - otherwise the total time is still accurate but phase breakdown is redacted by the browser.
FAQs
Why do the phase timings show 0 ms?
The target server didn't send Timing-Allow-Origin: *. Browsers redact detailed phase timings for cross-origin requests without that header - it's a privacy protection, not a bug.
Why does the request fail with a CORS error?
The browser refuses to expose the response to your JS when the server doesn't send Access-Control-Allow-Origin. You can still see the timing in DevTools Network tab, but the tool can't measure it. Try a public JSON API like api.github.com or jsonplaceholder.typicode.com.
Is this a real load test?
No. It's a single-client, sequential timer. For real load testing use k6, wrk or Locust.