Mozilla considers making Firefox DevTools a System Add-on

Martin Brinkmann
Jan 17, 2017

Mozilla is investigating options currently to turn the built-in Developer Tools of the Firefox web browser into a system add-on.

So-called system add-ons are browser add-ons that ship with core Firefox. Basically, add-ons that are not installed by the user but by Mozilla.

Firefox users have less control over these system add-ons, even though it is possible to remove them from the system Firefox is run on.

The main idea behind making the Developer Tools of the web browser a system add-on is that it allows Mozilla to deliver updates faster to users as the release of updates would not be tied to Firefox releases anymore.

firefox developer tools system addon

This is especially beneficial to users of Firefox's release channel who have to wait several release cycles currently to get updates (starting with Nightly, then Developer Tools, then Beta before they land in Stable). Mozilla notes that the majority of Developer Tools users use the release version of Firefox.

The DevTools team investigates scenarios currently in regards to turning the built-in Developer Tools into a system add-ons. One idea that is being discussed is to change the state of the Developer Tools when it is offered as a system add-on. The two main ideas are to either only install the system add-on on demand, or to ship it in disabled state instead, but both options are not supported right now by Firefox.

Move DevTools, DevEdition Prefs + Theme into a system add-on. This would allow us to achieve our goal of shipping to our users more quickly and set us to more easily transition all of our users later.

While Developer Tools are certainly appreciated by users who make use of them, the team notes that less than 1% of users interact with DevTools at all. A Microsoft study suggests on top of that, that the majority of users interact with the Developer Tools by mistake instead of intentionally.

Nothing is set in stone yet, but the team wants to move forward with the plan. There are also talks underway to transition the system later on to a mix of WebExtensions and system add-on.

(this is still up in the air) is likely that we transition from system add-on to WebExtension + System add-on. Where the system add-on becomes smaller and smaller, only remaining to support the WebExtension APIs we need and the rest of the tools to live as pure WebExtensions.

Closing Words

Turning the Developer Tools into a system add-on makes a whole lot of sense. First, it enables the team to push updates faster to all users as updates don't have to ride the train anymore to end up in the release version of the web browser.

Second, it may prevent users from interacting with the Developer Tools by mistake. As long as Mozilla gets the activation process right, it should not take more than one or two clicks to enable the Developer Tools in Firefox, doing so should be beneficial to all parties involved. (via Sören Hentzschel)

Now You: What's your opinion on the idea?

Mozilla considers making Firefox DevTools a System Add-on
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Mozilla considers making Firefox DevTools a System Add-on
Mozilla is investigating options currently to turn the built-in Developer Tools of the Firefox web browser into a system add-on.
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  1. Deklan said on January 17, 2017 at 12:29 pm

    I wonder, are system add-ons assumed to exist by some parts of the browser ? They are too difficult to see and disable for there not to be a reason. I wonder what it is. If their existence is assumed, then it is logical for feature stability that they are hard to see and disable. They’d only be add-ons so they can be updated faster than Firefox; something I disable, so basically for me, System add-on or not it’s once every six weeks.

    Regarding Dev Tools, why not, but have it turned into ONE WebExtension, not a thousand stupid elements that people have to find and download separately. That would be ridiculously counterproductive. As a web user, do I want to have to find and download separate modules for Video, for CSS, for WebGL ? No, obviously not. So as a web developer, do I want to download a module to inspect the DOM ? Another one to read out network requests ? Debug javascript ? Do Photoshop users want to hunt down and download separate modules to get access to layers ? Magic wand ?

    Developer tools are one. Make it a WebExtension if you like, it CAN actually benefit the tools for real, assuming that doesn’t mean a decrease in power on the long term because WebExt. Just keep it as one.

    Secondly, I don’t like the mandatory auto-downloading of features on demand, for privacy reasons. It’s convenient but if you are going that route, make sure you provide a user initiated way to download because some people don’t want you to know if they are using a feature: Those people disabled “telemetry” for a reason.

    That was for the critics. Now if the actual main goal is to improve developer tools, which I think it is, this is good news. On top of that, Dev Tools now have the Firebug team with them, so this sounds like a bright time for that part of Firefox. Not to mention I already consider Firefox Dev tools to be the best among browsers nowadays.

    1. Deklan said on January 17, 2017 at 1:24 pm

      I take back almost every critics I made. Apparently, they’re not talking about eventually splitting Dev Tools into several add-ons, the idea is just to make it a system add-on that is gradually turned into a WebExtension as more API become available. It’s not a feature split. Dunno what made me misunderstand.

      Remains the on-demand issue: if clicking on Tools > DevTools downloads the thing and installs it, that doesn’t sound different from grabbing it on AMO. In that case it’s probably fine. On-use download of features can be used for data collection, but in that specific case I don’t think so.

      So basically I don’t have anything bad to say about this move so long as WebExt doesn’t mean that Dev Tools’ power and growth will become limited by a glass ceiling in a few years. (I assume it would keep a system add-on component, if that was to be the case)

      Goes to show how much not being properly informed leads to making useless critics and stupid opinions. Well done Deklan.

  2. Dave said on January 17, 2017 at 10:55 am

    Good. Throwing that thing it a normal user if they accidentally hit F12 is ludicrous.

    Oh wait, it’s still gonna do that. In that case.. doesn’t seem to matter. I take it system add-ons can still use XPCOM?

  3. Pants said on January 17, 2017 at 10:33 am

    I’m all for it, but I’d also like more control in the interface to be able to deal with System Addons ( ). Martin has already had an article on this( )

    1. Tom Hawack said on January 17, 2017 at 8:46 pm

      Hi there, Pants. I remove system add-ons whenever I update Firefox, but I thought the add-on manager was now able to disable system add-ons as well… otherwise remains the CCleaner option as we know.

      Anyway, personally, I’m of the less than 1% of users that don’t interact with DevTools, so I’d welcome this feature as a system add-on for that reason. Otherwise I’d welcome it as well for the reasons mentioned in the article.

      What I ignore is if having DevTools as a non-installed/disabled system add-on may have an impact on other add-ons which would refer to them.

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