Test Profiles

Test Profiles allow you to change the conditions that your site is tested under.

Calibre is able to emulate popular devices (like iPhones, iPads and Nexus phones), throttle network connectivity, set custom headers or cookies, run with an adblocker or completely block third-party code.

Test profiles can be found for each site in Calibre by navigating to Site → Settings → Test Profiles.

Emulated devices

Device emulation is achieved using Google Chrome’s device emulation—we go a few further steps to ensure that the experience is as close to a real device as possible.

Calibre is able to emulate the following devices:

  • Motorola Moto G4
  • iPhone 5
  • iPhone 6
  • iPhone 6 Plus
  • iPhone 7
  • iPhone 8
  • Nexus 5X
  • Nexus 6P
  • Galaxy S5
  • iPad
  • iPad Pro

When Calibre emulates a device, the following occurs:

  • The device viewport is changed.
  • The User-Agent is set to that of the device.
  • The CPU will be slowed to reflect the hardware conditions of the device.

Emulated network connection speed

Calibre limits the bandwidth available to the browser by using pre-configured network speed options that best reflect average global connectivity.

Those pre-configured options are:

No bandwidth throttling
Regular 2GLatency: 300ms31.25 KB/s6.25 KB/s
Good 2G150ms56.25 KB/s18.75 KB/s
Regular 3G100ms93.75 KB/s31.25 KB/s
Good 3G40ms192.00 KB/s93.75 KB/s
DSL5ms256.00 KB/s128.00 KB/s
Regular 4G20ms512.00 KB/s384.00 KB/s
WiFi2ms3.75 MB/s1.88 MB/s


Custom cookies can be added to a Test Profile.

Heres a few things that you could do with cookies:

  • Authenticate Calibre to your web app.
  • Disable advertising to ease troubleshooting of dev specific regressions.
  • Test against an A/B test or staff-shipped feature.


Custom headers can be set via Test Profiles. This is useful for setting Authorisation headers for basic authentication or for triggering certain conditions for your pages.


Calibre’s agents are also able to test using an adblocker. If you’re curious to see how pages perform with or without ads this feature, create a new profile that blocks ads.

At the time of writing, Calibre’s adblocker is powered by uBlock.

Third Party Blocking

Calibre will automatically detect third party providers during testing and you can choose to block providers in test profiles.

A few good examples of Test Profiles to establish would be disabling:

  • Chat widgets and communication tools
  • Scripts providing polyfills
  • Analytics software
  • Bug tracking