How to read a WebPageTest waterfall chart

A presentation at FOSDEM21 by Matt Hobbs

WebPageTest is one of the most well-known and important tools in the web performance community. It’s been actively developed by Pat Meenan since he worked at AOL in 2008. It has become the go-to tool for both simple to very advanced debugging of the web performance of a website. One of its most well-known charts is the waterfall chart. In this talk, I’m going to introduce the waterfall chart and also go into detail on how you can examine and read it. The more you understand about the chart, the more WebPageTest as a whole will be able to help you fix a slow performing website.


The following resources were mentioned during the presentation or are useful additional information.

  • Video Download

    The video of the talk is available to download here.

  • How to read a WebPageTest Waterfall View chart

    WebPageTest waterfall charts are a mighty web performance tool, but can sometimes be a little confusing. Maybe this post can change that.

  • How to read a WebPageTest Connection View chart

    There’s more to WebPageTest than the Waterfall View. In this post, I look at the ‘Connection View’ and how it can be used to spot web performance issues.

  • How to run a WebPageTest test

    Let’s examine the WebPageTest homepage and investigate what all the settings do, including examples of what you can use them for.