No Longer Lost in Translation

9 popular extensions in 7 new locales


You might have noticed that while Firefox supports 90 languages, many extensions and their listings on (AMO) are only available in English.

At present, we don’t have a way to connect extension developers with the translation community at scale, and  Pontoon, Mozilla’s tool for localizing products and websites, currently only supports translating the AMO site itself.

What we do have, however, is a desire to make translation resources available, a longstanding and active community of localizers, and friends on Mozilla’s Open Innovation team who specialize in putting the two together. Part of Open Innovation’s work is to explore new ways to connect communities of enthusiastic non-coding contributors to meaningful projects within Mozilla. Together with Rubén Martín, we ran a campaign to localize an initial group of top Firefox extensions into the 7 most popular languages of Firefox users.

More than 100 multilingual Mozillians answered the call for participation and submitted more than 140,000 translated words for these extensions using CrowdIn, a localization platform most recently used for Mozilla’s Common Voice project. These translations were reviewed by a core team of experienced localizers, who then provided approved translations to developers involved in the campaign to include in their next version update.

Now, you can enjoy this collection of extensions in Chinese (simplified), Dutch, French, German, Italian, Portuguese (Brazilian),  and Spanish:

1-Click Youtube Download* · Adblock for Firefox · Download Flash and Video
Greasemonkey · New Tab Override · NoScript Security Suite
Pinterest Save Button · signTextJS plus · To Google Translate

While this campaign is limited to a small group of extensions, we hope to roll out a localization process for all interested extension developers in the near future. Stay tuned for more information!

If you would like to participate in future campaigns at Mozilla, subscribe to Mission-Mozillians-Campaigns tag on Discourse to learn how to get involved. If you are specifically interested in localizing other content for Mozilla, check out the L10n wiki to learn how to get started.

Many thanks to the extension developers and localizers who participated in this campaign.

* Coming soon! If you would like a localized version of this extension in one of the languages listed above, install the extension now. During its next update, you will be automatically switched to the version for your locale.

Upcoming changes for themes

Theming capabilities on (AMO) will undergo significant changes in the coming weeks. We will be switching to a new theme technology that will give designers more flexibility to create their themes. It includes support for multiple background images, and styling of toolbars and tabs. We will migrate all existing themes to this new format, and their users should not notice any changes.

As part of this upgrade, we need to remove the theme preview feature on AMO. This feature allowed you to hover over the theme image and see it applied on your browser toolbar. It doesn’t work very reliably because image sizes and network speed can make it slow and unpredictable.

Given that the new themes are potentially more complex, the user experience is likely to worsen. Thus, we decided to drop this in favor of a simpler install and uninstall experience (which is also coming soon). The preview feature will be disabled starting today.

It’s only a matter of weeks before we release the new theme format on AMO. Keep following this blog for that announcement.

New Site for Thunderbird and SeaMonkey Add-ons

When Firefox Quantum (version 57) launched in November 2017, it exclusively supported add-ons built using WebExtensions APIs. (AMO) has followed a parallel development path to Firefox and will soon only support WebExtensions-based add-ons.

As Thunderbird and SeaMonkey do not plan to fully switch over to the WebExtensions API in the near future, the Thunderbird Council has agreed to host and manage a new site for Thunderbird and SeaMonkey add-ons. This new site,, will go live in July 2018.

Starting on July 12th, all add-ons that support Thunderbird and SeaMonkey will be automatically ported to The update URLs of these add-ons will be redirected from AMO to the new site and all users will continue to receive automatic updates. Developer accounts will also be ported and developers will be able to log in and manage their listings on the new site.

Thunderbird or SeaMonkey add-ons that also support Firefox or Firefox for Android will remain listed on AMO.

If you come across any issues or need support during the migration, please post to this thread in our community forum.

Extensions in Firefox 62

Last week Firefox 62 moved into the Beta channel. This version has fewer additions and changes to the WebExtensions API than the last several releases. Part of that is due to the maturing nature of the API as we get farther away from the WebExtension API cutover back in release 57, now over seven months ago. Part of it was a focus on cleaning up some internal features — code changes that increase the maintainability of Firefox but are not visible to external developers. And, let’s be honest, part of it is the arrival of summer in the Northern hemisphere, resulting in happy people taking time to enjoy life outside of browser development.

User Interface Improvements

Extensions with a toolbar button (browser action) can now be managed directly from the context menu of the button.  This is very similar to the behavior with page actions – simply right click on the toolbar button for an extension and select Manage Extension from the context menu.  This will take you to the extension’s page in about:addons.

Manage Extension Context Menu

You can now manage hidden tabs, introduced in Firefox 61, via a down-arrow that is added to the end of the tab strip. When clicked, this icon will show all of your tabs, hidden and visible.  Firefox 62 introduces a new way get to that same menu via the History item on the menu bar. If you have hidden tabs and select the History menu, it will display a submenu item called “Hidden Tabs.”  Selecting that will take you to the normal hidden tabs menu panel.

Hidden Tabs Menu

API Improvements

A few enhancements to the WebExtensions API are now available in Firefox 62, including:

Theme Improvements

A couple of changes to the WebExtensions theme API landed in this release:

Tab Background Separator

Bug Fixes

A few noticeable bug fixes landed in Firefox release 62, including:

Thank You

A total of 48 features and improvements landed as part of Firefox 62. As always, a sincere thank you to every contributor for this release, especially our community volunteers including Tim Nguyen, Jörg Knobloch, Oriol Brufau, and Tomislav Jovanovic. It is only through the combined efforts of Mozilla and our amazing community that we can ensure continued access to the open web. If you are interested in contributing to the WebExtensions ecosystem, please take a look at our wiki.


July’s Featured Extensions

Firefox Logo on blue background

Pick of the Month: Midnight Lizard

by Pavel Agarkov
More than just dark mode, Midnight Lizard lets you customize the readability of the web in granular detail—adjust everything from color schemes to lighting contrast.

“This has got to be the best dark mode add-on out there, how is this not more popular? 10/10”

Featured: Black Menu for Google

by Carlos Jeurissen
Enjoy easy access to Google services like Search, Translate, Google+, and more without leaving the webpage you’re on.

“Awesome! Makes doing quick tasks with any Google app faster and simpler!”

Featured: Authenticator

by mymindstorm
Add an extra layer of security by generating two-step verification codes in Firefox.

“Thank you so much for making this. I would not be able to use many websites without it now days, literally, since I don’t use a smartphone. Thank you thank you thank you. Works wonderfully.”

Featured: Turbo Download Manager

by InBasic
A download manager with multi-threading support.

“One of the best.”

Featured: IP Address and Domain Information

by webdev7
Know the web you travel! See detailed information about every IP address, domain, and provider you encounter in the digital wild.

“The site provides valuable information and is a tool well worth having.”

If you’d like to nominate an extension for featuring, please send it to amo-featured [at] mozilla [dot] org for the board’s consideration. We welcome you to submit your own add-on!

Larger image support on

Last week, we pushed an update that enables add-on developers to use larger image sizes on their add-on listings.

We hadn’t updated our size limits for many years, so the images on listing pages are fairly small. The image viewer on the new website design scales the screenshots to fit the viewport, which makes these limitations even more obvious.

For example, look at this old listing of mine.

Old listing image on new site

The image view on the new site. Everything in this screenshot is old.

The image below better reflects how the magnified screenshot looks like on my browser tab.

All of the pixels


After this fix, developers can upload images as large as they prefer. The maximum image display size on the site is 1280×800 pixels, which is what we recommend they upload. For other image sizes we recommend using the 1.6:1 ratio. If you want to update your listings to take advantage of larger image sizes, you might want to consider using these tips to give your listing a makeover to attract more users.

We look forward to beautiful, crisper images on add-on listing pages.

Add-ons at the San Francisco All Hands Meeting

Last week, more than 1,200 Mozillians from around the globe converged on San Francisco, California, for Mozilla’s biannual All Hands meeting to celebrate recent successes, learn more about products from around the company, and collaborate on projects currently in flight.

For the add-ons team, this meant discussing tooling improvements for extension developers, reviewing upcoming changes to (AMO), sharing what’s in store for the WebExtensions API, and checking in on initiatives that help users discover extensions. Here are some highlights:

Developer Tools

During a recent survey, participating extension developers noted two stand-out tools for development: web-ext, a command line tool that can run, lint, package, and sign an extension; and about:debugging, a page where developers can temporarily install their extensions for manual testing. There are improvements coming to both of these tools in the coming months.

In the immediate future, we want to add a feature to web-ext that would let developers submit their extensions to AMO. Our ability to add this feature is currently blocked by how AMO handles extension metadata. Once that issue is resolved, you can expect to see web-ext support a submit command. We also discussed implementing a create command that would generate a standard extension template for developers to start from.

Developers can currently test their extensions manually by installing them through about:debugging. Unfortunately, these installations do not persist once the browser is closed or restarted. Making these installations persistent is on our radar, and now that we are back from the All Hands, we will be looking at developing a plan and finding resources for implementation. (AMO)

During the next three months, the AMO engineering team will prioritize work around improving user rating and review flows, improving the code review tools for add-on reviewers, and converting dictionaries to WebExtensions.

Engineers will also tackle a project to ensure that users who download Firefox because they want to install a particular extension or theme from AMO are able to successfully complete the installation process. Currently, users who download Firefox from a listing on AMO are not returned to AMO when they start Firefox for the first time, making it hard for them to finish installing the extension they want. By closing this loop, we expect to see an increase in extension and/or theme installations.

WebExtensions APIs

Several new and enhanced APIs have landed in Firefox since January, and more are on their way. In the next six months, we anticipate landing WebExtensions APIs for clipboard support, bookmarks and session management (including bookmark tags and further expansions of the theming API).

Additionally, we’ll be working towards supporting visual overlays (like notification bars, floating panels, popups, and toolbars) by the end of the year.

Help Users Find Great Extensions Faster

This year, we are focusing on helping Firefox users find and discover great extensions quickly. We have made a few bets on how we can better meet user needs by recommending specific add-ons. In San Francisco, we checked in on the status of projects currently underway:

Recommending extensions to users on AMO

In May, we started testing recommendations on listing pages for extensions commonly co-installed by other users.

A screenshot of the recommender feature on AMO.

Results so far have shown that people are discovering and installing more relevant extensions from these recommendations than the control group, who only sees generally popular extensions. We will continue to make refinements and fully graduate it into AMO in the second half of the year.

(For our privacy-minded friends: you can learn more about how Firefox uses data to improve its products by reading the Firefox Privacy Notice.)

Adding extensions to the onboarding tour for new Firefox users.

We want to make users aware of the benefits of customizing their browser soon after installing Firefox. We’re currently testing a few prototypes of a new onboarding flow.

And more!

We have more projects to improve extension discovery and user satisfaction on our Trello.

Join Us

Are you interested in contributing to the add-ons ecosystem? Check out our wiki to see a list of current contribution opportunities.


June’s Featured Extensions

Firefox Logo on blue background

Pick of the Month: Tabliss

Enjoy a gorgeous new tab page with customizable background images and many informational widgets to choose from, like local weather, date/time, bookmarks, and more.

“Wow. Absolutely stunning without the need for advanced user input to make it stunning.”

Featured: View Page Archive & Cache

by Armin Sebastian
Find archived and cached versions of older web pages with the help of multiple search engines, like Wayback Machine, Google Cache, Bing Cache, and others.

“Outstanding! Often have to search multiple sites for cached pages. Very useful time-saver for me. Thank you!”

Featured: Share Backported

by Daniele Mte90 Scasciafratte
Older versions of Firefox included a social media ‘share’ button in the Toolbar. This extension brings it back to its original glory.

“Beautifully implemented!”

If you’d like to nominate an extension for featuring, please send it to amo-featured [at] mozilla [dot] org for the board’s consideration. We welcome you to submit your own add-on!

Extensions in Firefox 61

Firefox 60 is now in the Release channel, which means that Firefox 61 has moved from Nightly to the Beta channel. As usual, Mozilla engineers and volunteer contributors have been hard at work, landing a number of new and improved WebExtensions API in this Beta release.

Before getting to the details, though, I’d like to note that the Firefox Quantum Extensions Challenge has come to an end.  The contest was a huge success and the judges (myself included) were overwhelmed with both the creativity and quality of the entrants.  A huge thank you to everyone who submitted an extension to the contest and congratulations to the winners.

The Case of the Vanishing Tabs

In November of 2017, we made a commitment to enriching the WebExtensions API with additional tab management features, with tab hiding being a top priority.  Since that time, several new and enhanced tab-related API have been added and today, with the release of Firefox 61 to the Beta channel, tab hiding is officially a WebExtensions API.

The usage of the tabs.hide() API was covered in the post on Extensions in Firefox 59.  The main change now is that it is no longer necessary to set the extensions.webextensions.tabhide.enabled preference to true; tab hiding can be used by extensions without setting that preference. In fact, that preference will soon be going away in an upcoming release.

In the user interface, when tabs are hidden, a down-arrow is added to the end of the tab strip. When clicked, this icon shows all of your tabs, hidden and visible, and provides a quick and easy way to keep from losing things (see animation below, and thanks to Afnan Khan for the great Hide Tabs extension).

Hidden Tabs Arrow

In addition, if a hidden tab is playing audio, the audio icon is shown on top of the down-arrow icon.  If you click on the down-arrow, the hidden tab with audio is pulled out so that it is easier to find (see animation below).

Audio Icon For Hidden Tabs

You can expect to see this user interface get a small update in Firefox 62. In particular, it will be modified so that it conforms to the Firefox Photon Design System.

Making Hidden Tabs Visible

As noted above, when an extension hides a tab, Firefox will display a down-arrow in the tab strip that gives users access to all of their tabs, both visible and hidden. This is a simple and easy way to manage hidden tabs, but it is also subtle.  To make sure users are completely aware of hidden tabs, and to discourage malicious and deceitful use of them, Firefox will always show a door hanger when the first tab is hidden.

Hidden Tab Door Hanger

The door hanger informs the user that one or more tabs was hidden by an extension, explains the down-arrow on the tab strip (pointing to it), and gives the user the option to disable the extension.

Even More Tab Stuff

While tab hiding is the biggest feature to land in Firefox 61, a few other highly requested tab features also made it into this release.

A new browserSettings API, openUrlbarResultsInNewTabs, allows extensions to specify if search results from the URL bar should open in the current tab or a new tab.  This complements the existing browserSettings.openBookmarksInNewTabs and browserSettings.openSearchResultsInNewTabs settings.

Also, fine grain control of the opening position for new tabs is now provided via the browserSettings.newTabPosition API.  This new API can take three different values:

  • afterCurrent – open all new tabs next to the current tab
  • relatedAfterCurrent – open child tabs (tabs opened from a link in the current tab) after the current tab
  • atEnd – open all new tabs at the end of the tab strip

Finally, listeners to the tabs.onUpdated event can now supply a filter to avoid the overhead of unwanted events. The filter supports URLs, window and tab ids, and various properties such as “audible”, “discarded”,  “hidden”, “isarticle” and more. Not only does this simplify code inside the listener for developers, it significantly improves browser performance by keeping Firefox from dispatching so many events. Extension developers are strongly encouraged to use this new feature to make their extension and the browser more performant for users.


It seems we can’t let a release go by without adding to themes, and Firefox 61 is no exception. Check out the new improvements (and the improved documentation on MDN that shows examples of what each theme property modifies).

  • Themes support default_locale; not a theme property, but a standard manifest key
  • Fixed tab_selected so it works when headerURL is not set (uplifted to 60)
  • Fully transparent values are once again allowed in themes
  • All of the toolbar properties now apply to the find bar as well
  • Themes can now set the hover, active and focus colors for buttons and toolbars
  • Autocomplete popups now honor any popup_* theme properties that are set

Cleaning the WebExtensions House

I usually end each blog post with a small section that notes some of the general improvements and/or bug fixes in the release. For Firefox 61, though, there was a concerted to improve the WebExtensions ecosystem.  A substantial number of bug fixes and optimizations landed, enough that I wanted to make sure they were more than just a footnote.

Keeping The User Informed

In addition to making sure users are fully aware of extensions using tab hiding, Firefox 61 also highlights when an extension modifies a user’s Home page by displaying a door hanger.

And to help users better understand when an extension is controlling the New Tab page or Home page, or using the tab hiding feature, the door hanger now shows the name of the controlling extension and includes a “Learn More” link that takes the user to a more detailed explanation on Mozilla’s support site.

New Home Page Door Hanger

Important Proxy Changes

After the release of Firefox 59, we discovered that the implementation of the proxyConfig API was not handling the settings for hostnames correctly, causing non-socks proxy settings to fail. The has been corrected in Firefox 61 and uplifted to Firefox 60.

The discovery and resolution of this bug, however, caused us to reevaluate how WebExtensions exposed proxy settings.  In particular, we asked ourselves why these settings weren’t part of the browser.proxy.* namespace. It is true that the underlying implementation depends upon Firefox browser settings, which is how it ended up as part of the browser.browserSettings.* namespace, but that’s just an internal detail. Every major browser vendor supports proxy settings, and they all support basically the exact same set of settings.

Given that, and the fact that Mozilla should be championing web standards, we decided it made more sense to have the proxy settings live inside the browser.proxy.* namespace. So starting with Firefox 60, the browser.browserSettings.proxyConfig API is now the browser.proxy.settings API.  Extensions developers who want to use this API should request the much more intuitive “proxy” permission instead of the “browserSettings” permission.

Finally, another patch was landed in Firefox 61 so that proxy extensions can start before requests bypass them.

Browser Settings

A few new browser settings are now available to extension developers in Firefox 61:

  • Extensions can now toggle the setting that decides if pages should be rendered with document fonts or not via browserSettings.useDocumentFonts.
  • Along similar lines, extensions can set the preference that decides if a page should be rendered with the document colors, user-selected colors, or user-selected only with high-contrast themes via the browserSettings.overrideDocumentColors API.
  • Extensions can offer users the ability to close tabs by double-clicking them via the browserSettings.closeTabsByDoubleClick API.

Thank You

This was a busy release for the WebExtensions API with a total of 95 features and improvements landed as part of Firefox 61. A sincere thank you goes to our many contributors for this release, especially our community volunteers including: Tim Nguyen, Oriol Brufau, Vivek Dhingra, Tomislav Jovanovic, Bharat Raghunathan, Zhengyi Lian, Bogdan Podzerca, Dylan Stokes, Satish Pasupuleti, and Sören Hentzschel. It is only through the combined efforts of Mozilla and our amazing community that we can ensure continued access to the open web. If you are interested in contributing to the WebExtensions ecosystem, please take a look at our wiki.

Switching to JSON for update manifests

We plan on switching completely to JSON update manifests on Firefox and AMO. If you self-distribute your add-on please read ahead for details.

AMO handles automatic updates for all add-ons listed on the site. For self-hosted add-ons, developers need to set an update URL and manage the update manifest file it returns. Today, AMO returns an RDF file, a common legacy add-on feature. A JSON equivalent of this file is now supported in Firefox. JSON files are smaller and easier to read. This also brings us closer to removing complex RDF parsing from Firefox code.

Firefox 62, set to release September 5, 2018, will stop supporting the RDF variant of the update manifest. Firefox ESR users can continue using RDF manifests until the release of Firefox 68 in 2019. Nevertheless, all developers relying on RDF for their updates should read the documentation and switch soon. Firefox 45 introduced this feature, so all current versions of Firefox support it.

Developers of add-ons hosted on AMO don’t need to take any action. AMO will switch to JSON updates in the coming weeks. You don’t need to make any changes for add-ons hosted on AMO to update normally. Users on versions of Firefox older than 45 will no longer receive automatic updates. However, that should be a very small number of users. It’s also a very small number of active add-ons, since Firefox 45 predates the move to WebExtensions.

If you have any questions about this, please post a comment on the Discourse thread.