WebPagetest.org – top tool

March 5, 2010 8:04 am | 12 Comments

I’m loving WebPagetest.org. In Even Faster Web Sites I said, “[WebPagetest] hasn’t gotten the wide adoption it deserves.” It got a boost after Matt Cutts mentioned WebPageTest.org in his interview with WebProNews. But I still meet people who aren’t aware that this great performance tool is out there, so let me bang their drum some more.

Pat Meenan and Eric Goldsmith are the team behind AOL Pagetest and WebPagetest.org. AOL Pagetest is the Windows tool that works in IE. Pat took that and put it behind a web server running in his basement and called it WebPagetest. That was two years ago. He took the Open Source route and now there are instances of WebPagetest running in Virginia, California, UK, China, and New Zealand hosted by AOL as well as Strangeloop Networks, Aptimize, and Daemon Solutions.

The power of WebPagetest.org is that it’s web-based – you don’t have to do any installs and you can run it on any OS and browser. On the backend, WebPagetest runs the page in either IE7 or IE8 and displays the results. This might be a limitation for some folks – if you want to test a page on Mac OS X using Safari you’ll have to do that with some other tool. But the fact that IE 7&8 are the dominate browsers means you can see the most typical experience regardless of what platform you’re currently working on. Since many developers work on Mac using Safari or Firefox, and more are moving to Chrome, it’s important that they can easily see how their web pages load for a majority of their users.

New Test

Here’s how it works: Go to the New Test tab. Enter the URL you want to test and click submit. Pretty easy! 90% of the time that’s what I do, but there are other options you can tweak:

  • pick a geo location – VA, CA, UK, CN, or NZ
  • choose IE7 or IE8
  • choose a connection speed – Dial, DSL, FIOS (Dial and DSL are done via throttling)
  • test just the first (empty cache) page load or first and repeat
  • repeat the test up to 10 times to get a bigger sample size
  • opt to keep your test results private if desired


The results page shows summary stats (page load times, bytes downloaded, # of HTTP requests) and a mini performance analysis (compression, image optimization, concatenating scripts and stylesheets). But the piece I love is the waterfall chart.

If you click on the mini waterfall, it takes you to a larger view where you can do additional customizations. I’ve been relying on this for my current series of blog posts on P3PC (performance of 3rd party content). And Pat even added a few options I requested. You can set the size of the image, remove certain requests (for example, I sometimes remove favicon.ico), and whether to show the extra bits on CPU and bandwidth utilization. I end up with clean waterfall charts like this:

And there’s more – Video!

When you create a new test, you can opt to record a video of the page loading (go to the Video tab under “Step 4 – Test Options” in the figure above). WebPagetest generates a filmstrip of images as well as a video. The image filmstrip shows what the page looks like as it loads. You can choose different time increments (0.1, 0.5, 1 and 5 seconds). Wikipedia is pretty straightforward as it loads. Here’s the filmstrip for FOX Sports. Content arrives in the 0-5 second range, more images (like the logo) are filled in from 5-10 seconds, and flash arrives by the 15 second mark. You can also view the video.

Pat does a lot of this work on his own time and all the video features are in Alpha, so be tolerant. I use WebPagetest.org daily and it has become one of my favorite performance tools. Definitely give it a try.

12 Responses to WebPagetest.org – top tool

  1. Thanks for the props.

    It really is a community-driven site so if there is something you wish it could do just send it my way (or even feel free to bang on the code). Most of the cool features came from user requests (the filmstrip view for example was totally Steve’s idea).

    The test locations are also community hosted so if you’d like to see testing from somewhere else on the globe and know someone with a spare machine there that would like to run a test location just send them my way.

  2. Wow, very nice tool indeed! I really like the performance breakdown per file!

  3. Agreed this is a really slick tool that probably doesn’t get the coverage it deserves. I’ve used a few times and have been very impressed with the amount of information it provides, at a very detailed level.

    Not sure what it will take to add support for other browsers, but that would probably be at the top of my feature request list.

  4. Yeah, other browsers is on the list of things I really want to get done but it’s a pretty big effort and I’ve mostly been working on things that I can get done in little chunks.

    Firefox, Chrome and Safari (all Windows) – in that order is the plan and not all of the capabilities will be there from the start but hopefully I can come up with a good way to do it generically. I may have to ditch https/SSL support for an initial cut which will make it much easier to do generically.

  5. I think the waterfall view is better than any other tool.

  6. Also you can install the tool at work if you want to test websites that are not accessible over the internet. (though you’ll have to simulate low bandwith !)

    It’s opensource : http://dev.webpagetest.org/

  7. I strongly recommand this tool.
    I you have the knowledge, you can install it on your server, it’s a very great tool to use.

    Patrick is always available to help you on the forum.

  8. FWIW, the dev.webpagetest.org urls are for the TRAC instance. The code is here: http://code.webpagetest.org/svn/ though it’s probably easier if you use the packaged installers that I release in the forums (granted, they get a bit out of date between releases).

    Simulating the bandwidth also just got a bunch easier as DUMMYNET was just released for Windows so you can set up traffic shaping directly on the test machines: http://info.iet.unipi.it/~luigi/dummynet/

  9. Dummynet works very well on windows, thanks a lot, before that i was simulating trafic from server (wich was on linux so easier…)

  10. Patrick is always available to help you on the forum.

  11. What is the principle cause of the time to first byte values for the png files (or other static resources) in the example above for wikipedia. My sites have a similar profile… basically all of the time is spent in the Time To First Byte phase.

    any suggestions would be appreciated.

  12. I am also a big fan of Webpagetest.org, I wrote a post about it here: http://david-franklin.net/2010/12/website-optimization-with-wepagetest/

    But I did not know about the video option, I will have to check that out, it sounds pretty interesting.