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Browser Options and Emulation

  • 3 minutes to read

Browser Command Line Flags

You can specify browser launch options in the Run Configuration Dialog. Expand Browser Options and specify the flags in the CLI flags field.

Browser Options in the Run Configuration Dialog


For a list of browser options, refer to the following resources:

Note that Safari does not support command line flags.

Device Emulation

Chromium and Chromium-based browsers (Google Chrome, Microsoft Edge) include a device emulator.

To enable the emulator, open the Run Configuration Dialog, expand the Browser Options tab, and specify emulation settings.

Device Emulation in the Run Configuration Dialog

Join the name of the parameter and its value with the equals sign (=). Separate parameters with semicolons (;) - do not use spaces.

Emulate a Device

Specify the target device with the device parameter.

Specify the Device Name


See the full list of supported devices in DevTools -> ⋮ -> Settings -> Devices

Emulate Screen Size

You can specify parameters such as width, height, or orientation to configure the emulator.

Specify Screen Size to Emulate

Custom User Agent

Use the userAgent parameter to specify a custom user agent string.


Invalid or incompatible user agent strings may lead to test errors. Escape semicolons (;) with double backslashes.

Specify User Agent to Emulate

Emulation Parameters

Use the following parameters to configure the Chromium device emulator. Specify them after the emulation parameter as in the examples above.

Parameter Type Description Default
device (optional) String The name of the device (see the full list of supported devices in DevTools -> ⋮ -> Settings -> Devices). No default value.
width (optional) Number The device screen width in pixels. The width of the device. If the device parameter is not set, the default browser width is used.
height (optional) Number The device’s screen height in pixels. The height of the selected device. If the device parameter is not set, the default browser height is used.
scaleFactor (optional) Number Device scale factor value. Depends on the selected device or your system parameters.
mobile (optional) Boolean Defines whether to emulate a mobile device. This includes the viewport meta tag, overlay scrollbars, text autosizing, etc. true if a mobile device is set using the device property. Otherwise, false.
orientation (optional) vertical | horizontal The device orientation vertical
userAgent (optional) String The user agent string The user agent string of the selected device or the browser.
touch (optional) Boolean Enables or disables touch event emulation. true if a touch-supported device is set via the device property or your system supports touch events. Otherwise, false.
cdpPort (optional) Number A port (0-65535) used for Chrome DevTools Protocol. 9222 if you enable Load user profile. Otherwise, TestCafe automatically assigns a free port.

User Profiles

TestCafe Studio starts browsers with an empty profile to ensure consistent test results on different machines. However, you can run tests with the current user profile in Chromium browsers and Firefox.

To do this, enable the Load user profile setting in the Browser Options section of the Run Configuration dialog.

The "Load user profile" check box in the Run Configuration dialog


You cannot load the current user profile in headless mode.