I have, up to now always thought that Firefox for Android (codenamed Fennec) uses much of the same codebase as the Firefox for Desktop (Linux/Mac/etc...). However this recent post on HackerNews makes me think I might have got this wrong.

This marks the last Android release with extensions/add-on support. There will not be a 69 release of this edition of Firefox for Android ("Fennec").

I am of course concerned about the add-ons support, but also remain confused, to the best of my understanding Firefox on the Desktop systems has already been using the changed new Web-Extension API, has Fennec not supported this, and more importantly:

is Fennec something different (if so how) to the Desktop Version of Firefox (which I suppose is gradually becoming more Quantum).?

2 Answers 2


Fennec (<=68) is being phased out in favour of Fenix (>=69).

From that standpoint, Fennec will be "frozen" at version 68 and will not be updated to the engine used by the desktop version of Firefox 69.

Fenix will, at some point in the future, replace the current version of Firefox Android and is slated to begin at version 69, with some overlap with version 68.

Fenix features a largely rewritten architecture and engine and brings a lot of potential benefits, but the existing Fennec is pulling too much developer time away from it and causing problems in both camps. As a result it seems they want to draw a line in the sand, call an effective halt to Fennec and move over the majority or developers time.

Android Police have some more information detailing the change.

One of the things not currently supported in Fenix is extension support, and it is for that reason that the article you list states that Fennec is "the last Android release with extensions/add-on support."

It is currently unclear, as far as I can see, as to what the intention actually is with regards to extension support in the future. It may well be that if we choose to upgrade in the meantime that extensions are lost temporarily but, short of Firefox following Googles lead with regard to crippling the extension system, I would expect them to return at some point.

It does appear that there is still some discussion going on and that feature parity with the current version (Fennec/68) is intended.

The mobilisation of developer time might actually turn this feature from "nice to have but low priority" to being actively worked on.

  • So can I understand you answer that Fennec may or may not have had features subsumed under "Firefox Quantum" already? It however is different to Firefox Desktop enought that it takes additional developer time. Time that should be now spend for its successor Fenix (which albeit will lack web-extension support, even though web-extensions are already the "painful loss taken" for the Firefox Quantum, which lost the orignal/legacy extensions)? Commented Jul 10, 2019 at 12:23
  • I've only recently switched back to Firefox Mobile since I found that Greasemonkey and userscripts work perfectly on it. The performance is definitely well above what I experienced previously so I had assumed that the Quantum engine improvements were there and the Wikipedia page also seems to corroborate: en.m.wikipedia.org/wiki/Firefox_for_Android in the release history section "Version 57.0: November 14, 2017. First version based on Quantum project."
    – Mokubai
    Commented Jul 10, 2019 at 12:37
  • thanks for that piece of information. I asked that question because of the confusion regarding "Extensions and Quantum engine". It seems that Quantum (with Electrolisis multi-process) when introduced (also in Fennec as you mention) slaughtered many extensions and was unpopular. The link to HN above featured some replies that mentioned Quantum being the reason for the no extension in Fenix, when indeed I was thinking that Quantum is already in Fennec. It seems Fenix is something completely new, yet also based on the Quantum, which fennec is already. Commented Jul 10, 2019 at 12:42
  • I can see why the loss of extensions was a problem in the past and the loss of them again in another system is a problem, but most of what I can find suggests that like last time it is a short term problem and is being dealt with. The timeline doesn't look to be set in stone either so things are happening. That HN article seems to be being needlessly fatalistic.
    – Mokubai
    Commented Jul 10, 2019 at 13:12

Fennec: Firefox for Android (based in FF version 68.x). Fenix: Firefox for Android (based in FF version above 69.x

Fenix is based in Android Components and GeckoView (Firefox Quantum engine)

Curiously the usage of names can be a little bit confusing because the app "Fennec" (from F-Droid) at the moment is based on the latest Firefox( Fenix).

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