I want to enable webgl in the Tor Browser 8.0.6. In about:config, all settings are saved except webgl.min_capability_mode, which is always set to true. Whatever I do, this value is always set true. All other webgl.*-changes are persistent. I tried adding a new default profile with a custom user.js file, without any success.

How can I achieve webgl.min_capability_mode set to false on startup in the Tor Browser 8.0.6? Is this a bug or a feature?

migrated from security.stackexchange.com Mar 19 at 11:23

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The option being "true" is somewhat a feature of TOR Browser. According to Mozilla Developer Docs,

WebGL (Web Graphics Library) is a JavaScript API for rendering interactive 3D and 2D graphics within any compatible web browser without the use of plug-ins.


A Boolean property that, when true, enables a minimum capability mode. When in this mode, WebGL is configured to only support the bare minimum feature set and capabilities required by the WebGL specification.

TOR Browser wants to minimize users' digital fingerprint by disabling JavaScript for every websites. As in the quoted docs, WebGL is a JavaScrpit API. So, webgl.min_capability_mode: "true" is default value. To make it false, here TOR can be customized with autoconfig.

Assume the TOR is installed in C:\Tor folder. Create autoconfig.js file in C:\Tor\defaults\pref\autoconfig.js path with these lines:

// This line is a comment
pref("general.config.filename", "firefox.cfg");
pref("general.config.obscure_value", 0);

Create firefox.cfg file in C:\Tor\mozilla.cfg path. Add these following lines:

// This line is comment
lockPref("webgl.min_capability_mode", false);

The file name should match with the previous preference in autoconfig.js. Here lockPref locks the preference to false. In my opinion, I am not suggesting to change the default value. TOR does this to anonymize user identity.

Further Readings:

  • It worked, thank you very much. I was puzzled because I could change some values and some not. Unfortunately, min_capability_mode is indeed very minimal, it breaks some pages. – Rainer Glüge Mar 19 at 16:13

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