Chapter 11. Private Instances

In Chapter 9, we discussed how to use WebPageTest’s API to submit tests, check their status, and retrieve the results.

Using the public API is a great way to get started with the API, but the number of tests you can run is limited to around 200 per day.


WebPageTest counts every first view and every repeat view as separate tests; scripted tests that involve more than one page currently count as a single test, but that’s likely to change in the future.

Once you start to automate testing, you’ll probably find that you want to test more pages more frequently. For example, you might want to measure how a site changes over time or test each build in a continuous integration process. Once you start testing frequently, a usage limit of 200 tests per day doesn’t stretch far.

The public site is shared among all users, and API tests run at a lower priority than tests submitted via the Web, so if many other people are testing at the location you want to use, you may have to wait for a while.


Dulles generally has more than one test agent for each browser, but most other locations only have a single agent that is often shared among all browsers.

There’s also the challenge that can only test publicly accessible URLs, so if the site you want to test is behind a firewall, you may be out of luck! Of course you could poke holes in your firewall or use a proxy service to reach sites behind a firewall, but the proxy service is likely to affect ...

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