Extra HTTP headers support during training and local runs

The desktop app (v1.4.11 or later) and mabl CLI (v1.12.38 or later) support passing extra HTTP headers during training sessions and local runs for browser tests.

Desktop app

In the desktop app, users can configure additional headers in the Preferences dialog (Edit > Preferences > HTTP headers) or (mabl > Preferences > HTTP headers on Mac). Proxy settings have also been moved under the Preferences dialog.

A few caveats and features:

  • mabl will convert the header key string to lower case before using it.
  • the Enabled checkbox allows users to temporarily disable a particular header without deleting it completely.
  • the Description column is purely for informational and documentation purposes and is not used during test execution.
  • the Save button saves both proxy and header settings.


In progress training sessions

Changes to extra HTTP headers require a restart of any in-progress training sessions. The desktop app does not need to be restarted, just close the Trainer and edit the test again.


New Preferences dialog

Once the extra headers configuration is complete, the desktop app will use it for both training sessions and local runs initiated from the app. The output of a local run will show any HTTP header keys used during the run. Values are not logged to prevent accidental exposure of confidential information.



The stand-alone mabl CLI now provides optional command-line argument --http-headers to specify extra headers during the local test run. The setting applies to headful and headless test runs.

mabl tests run --id nwgJTPhe3W_4i6i0Xmkg2Q-j --http-headers 'user-agent:Completely-Custom-Agent' 'other-header:other-header-value'