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API Response Time Tester

Hit an endpoint from your browser and see status, latency, headers, and a body preview — once, or 5 times for min/avg/max. Everything runs in your browser — nothing is proxied.

Heads up — CORS applies. This tool uses your browser's fetch, so it can only read responses from APIs that send CORS headers (most public JSON APIs do). If a request fails here, the API may still be perfectly healthy — the browser just wasn't allowed to read the response. For non-CORS endpoints, test from curl or a server instead.
Results appear here. Times are measured with performance.now() from request start to headers received.

About this tool

Measures wall-clock latency with performance.now() from the moment the request is sent until response headers arrive, with a 10-second timeout. The 5× mode runs sequentially and reports min/avg/max over the successful runs. Because it runs inside a browser page, results include browser overhead and are subject to CORS: a failure here means "the browser couldn't read it", not necessarily "the API is down".

Requests go directly from your browser to the URL you enter — nothing is proxied through or logged by this site.

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Found this useful? 113 free, browser-only tools by Yuvrajsinh Jadav — an engineer who ships production AI systems. No account, nothing sent anywhere.
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