What Is WebPageTest and How to Use It

Short answer

WebPageTest is a free online tool that runs detailed performance tests from real browsers in multiple locations. It produces waterfall charts, filmstrips, and advanced metrics.

How it works

You submit a URL and choose a test location, browser, and connection speed. WebPageTest launches a real browser, captures a video of the loading process, and records every network request.

Example

Run a test from a 3G connection in Mumbai on Chrome. The filmstrip shows exactly when content appears, and the waterfall reveals which resources block rendering.

Why it matters

WebPageTest provides more detail than synthetic tools. The ability to test from various global locations and devices makes it invaluable for understanding real-world performance.