Firefox/protocols

Adding a New Protocol

Note: This does not appear to work with the Snap-installed deployment of Firefox on Ubuntu. Something interferes with Firefox's ability to run the executable, though it is able to run some other executables such as the Zoom desktop client. One easy-ish workaround is to simply download the Firefox binary and execute that directly.

To add a new protocol -- e.g. wooz:// -- you add the following entries to about:config:

network.protocol-handler.app.<protocol> = <path to executable>
network.protocol-handler.expose.<protocol> = false
network.protocol-handler.external.<protocol> = true

...where in this case <protocol> would be wooz.

The value of the first line may be arbitrary, as Firefox will let you browse for the executable to use when handling a link.

(To add an item to about:config, search for it. The UI will give you the option to add or modify. [1])

Protocol handlers appear in Settings (about:preferences) under "Applications", and can be edited or deleted from there.

Links

Reference

• MozKB:
  • Register protocol: instructions for various versions of Firefox under different OSes, but doesn't explain what the config entries do
  • network.protocol-handler.app.(protocol): main article
  • network.protocol-handler.expose-all: setting this FALSE may result in Firefox asking permission to load "https" links on a per-domain basis, which isn't generally what we want.
  • network.protocol-handler.expose.(protocol)

Posts

• 2017-07-30 I want to register a custom protocol handler in Firefox/Linux @Mozilla Support