Firefox Hello is the first system add-on for Firefox

Martin Brinkmann
Dec 8, 2015
Updated • Dec 10, 2015

The most recent Nightly versions of the Firefox web browser ship with the first system add-on released for the browser. Firefox Hello, the browser's realtime chat component, has been turned into a system add-on.

Mozilla announced in mid-2015 that it would turn specific features of Firefox into system add-ons in the near future. The idea behind the move was to make updates to these features independent from browser updates.

If Mozilla wanted to update Firefox Hello in previous versions of Firefox for instance, it would have to release an update for the whole browser. The new method speeds up the delivery of updates for components turned into system add-ons

Another benefit of the add-on approach is that Mozilla may deliver features to a sample of Firefox's userbase for testing purposes.

Firefox System Add-ons

firefox hello system addon

Firefox 45 or newer systems ship with the first system add-on already. One core difference between regular add-ons and system add-ons is that system add-ons cannot be removed from the add-ons manager.

In fact, the current implementation does not even list Firefox Hello in the add-ons manager of the browser.

The about:support page however lists it as an extension. System add-ons are not installed in the user's profile directory but in the installation directory of Firefox.

The directory differs depending on the operating system used and the version of Firefox that is installed on the system. Windows users find the Nightly directory under C:\Program Files (x86)\Nightly\browser\features, and the regular Firefox directory under C:\Program Files (x86)\Firefox\browser\features instead.

firefox system addon loop

Please note that the latter won't list system add-ons until it reaches version 45 at the very least. In fact, the features directory does not even exist yet in any version of the web browser but the most recent Nightly versions.

Since system add-ons are placed in the installation directory, they are enabled for all profiles used on the system automatically.

While Mozilla may list system add-ons in the Add-ons Manager eventually, giving users controls to disable them, no such feature exists currently.

You may delete these add-ons however in the features directory, and the add-ons are removed from Firefox as a consequence. I cannot say yet if this is permanent, or if updates will add them again to the browser.

I will keep an eye on this and update the article if the add-on is added again to the browser at a later point in time.

Update: The system add-on is added again when the browser updates.

It would be great in my opinion if Mozilla would give users full control over system add-ons. Those who don't want to use certain features should be able to disable or even delete them permanently from the browser.

The next feature that is going to be turned into a system add-on is Pocket. (via Sören Hentzschel).

Firefox Hello is the first system add-on for Firefox
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Firefox Hello is the first system add-on for Firefox
Mozilla turned Firefox Hello, a chat component integrated directly into Firefox, into the first system add-on for the browser.

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  1. Moonchild said on January 10, 2016 at 1:49 am

    So, basically re-inventing the (previously deprecated) distribution/bundles and distribution/extensions, but then only for extensions Mozilla deems fit to bundle. OK.

  2. Sam said on December 9, 2015 at 10:56 am

    An interesting observation: with ‘xpinstall.signatures.required’ set to true (so add-ons must be signed), an unsigned add-on placed into that ‘/browser/features’ directory will still be loaded.

  3. Anonymous said on December 9, 2015 at 10:25 am

    Yay. This is how you add tertiaty features to Firefox. Well done Mozilla.

    As for them not being in Add-ons Manager, again that’s the right business choice. Anyone who wants to get rid of it will find the answer on Google in seconds.

    I just downdraded to 38 ESR anyway. 40 and above have too many bugs and the new auto-scroll bug during page load is unacceptable, not to mention the problems with the bookmarks toolbar now.

    Still, Firefox’s future is looking better and better recently… except for that XUL/XPCOM thing :/

  4. formnull said on December 9, 2015 at 4:47 am

    System add-ons cannot be removed since they are shipped as part of Firefox, and the Addons Manager cannot remove these files.

    There is a patch in to allow disabling system add-ons.

  5. Jason said on December 8, 2015 at 5:25 pm

    This is a case of Mozilla doing the wrong thing for the right reasons. I’m ok with “system addons” in principle, because they do offer several advantages to Firefox as well as the end user. My problem is with the specific components that Firefox has chosen to label as system addons. Hello and Pocket should never have been been bundled with the browser. And this is coming from a guy who used Pocket for a couple of years when it first came out.

  6. Ouroboros said on December 8, 2015 at 5:04 pm

    But webrtc gets to stay I expect. Keeping the bugs and holes in your daily browsing.

  7. insanelyapple said on December 8, 2015 at 3:40 pm

    Non-removable system extensions reminds me of some 3rd party crapware from few years ago that could get into Firefox and which wasn’t removable as well – it had a form of extensions with disabled (grayed out) remove/turn off button

    Anyway, their idea of feature-as-extensions was good but implementation is shitty and pointless as usual with Mozilla for longer while.

  8. ozar said on December 8, 2015 at 3:12 pm

    “It would be great in my opinion if Mozilla would give users full control over system add-ons. Those who don’t want to use certain features should be able to disable or even delete them permanently from the browser.”

    I’m in total agreement, Martin. In fact, if Mozilla adds it by default and end-users can’t completely remove it, “add-on” doesn’t even sound like the correct term for such so-called features. I tried a number of other browsers a few months back and found several that were usable, but none of them at that point gave me the satisfaction of Firefox, so back to the fox I went. It appears though that it won’t be long before I’m driven to a suitable and permanent replacement.

  9. Anonymous said on December 8, 2015 at 2:56 pm

    sadly, after “disabling” Pimpzilla firefox is not the same…..

    1. Ñ said on December 8, 2015 at 11:03 pm

      What! you called mozilla pimpzilla no! why argg so frustrating bah haha people here may act like this, believe me i called them mozzarella and people almost bite me through the screen.

  10. Daniel said on December 8, 2015 at 2:35 pm

    Wonder if there are stats of the number of these “Hello” users.

    Now that it seems Thunderbird might be going over to the group behind LibreOffice… perhaps we can hope for the day when the same will happen to Firefox. Yay!

    1. Dentonthebear said on December 8, 2015 at 6:47 pm

      While a lovely idea it is sadly unlikely to happen according to this:

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