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Mozilla today launched Firefox 66 for Windows, Mac, Linux, and Android. The release includes autoplaying content (audio and video) blocked by default, smoother scrolling, better search, revamped security warnings, WebAuthn support for Windows Hello, and improved extensions. The company says its main goal with this release is to reduce irritating experiences such as auto-playing videos, pop-ups, and page jumps.

Firefox 66 for desktop is available for download now on, and all existing users should be able to upgrade to it automatically. The Android version is trickling out slowly on Google Play. According to Mozilla, Firefox has about 300 million active users. In other words, it’s a major platform that web developers must consider.

Autoplaying content blocked by default

Firefox 66 introduces a Block Autoplay feature that stops audio and video from automatically playing when you reach a website. If you want to view the video, you’ll have to hit the play button. That said, you can add your favorite websites to a permissions list for an interruption-free experience (click the “i” with a circle in the address bar -> Permissions => Autoplay sound => Allow).


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Mozilla’s main goal is to remove the annoyance of sound blaring from your speakers. On sites that automatically mute the sound, the Block Autoplay feature will not stop the video from playing. The feature will also continue to play subsequent content on a given page if you’ve already manually hit play.

If this sounds familiar, it’s because Google Chrome gained a similar feature in April 2018, coinciding with the release of Chrome 66. Google’s implementation works a bit differently. Chrome ranks each website for you to determine if content should play automatically, and then you can override if you’d like. Mozilla has meanwhile chosen to block by default and let Firefox users unblock as they see fit.

Smoother scrolling and better search

Firefox 66 introduces scroll anchoring, which holds your spot on a page without interruption from slow-loading images or ads. Regardless of when an image or ad loads, the page remembers where you are. This eliminates annoying page jumps, hopefully resulting in smoother scrolling.

Next, you can now search within multiple tabs — just type % in the Awesome Bar or click on the tab overflow menu (plus sign), which appears when you have a large number of tabs open. If you have more than one device on Firefox Sync, you can search the tabs on your other devices, as well.

Also, you can now set your default search engine in Private Browsing mode (Preferences => Search => Default Search Engine). Searching in Private Browsing can be useful when you’d prefer your search history not be saved (surprise parties, gifts, and so on). When you open a new tab in Private Browsing, you’ll now see a search bar with your default search engine (Google, Bing,, DuckDuckGo, eBay, Twitter, or Wikipedia).

Windows, Mac, and Linux

In addition to all of the above, Firefox 66 for desktop also brings better security warnings and Web Authentication API (WebAuthn) support for Windows Hello. The security warnings have been updated to be “simple and straightforward on why the site might not be safe.” WebAuthn support for Windows Hello means that with the next Windows 10 update, users will be able to sign in to compatible websites without a password — using a fingerprint, facial recognition, a PIN, or a security key.

Also worth noting is the improved extensions experience. Previously, extensions stored their settings in individual JSON files, which took some time to load. Now they store their settings in a Firefox database, which results in faster loading sites.

Here’s the full Firefox 66 for desktop changelog:

  • Firefox now prevents websites from automatically playing sound. You can add individual sites to an exceptions list or turn blocking off.
  • Find a specific webpage faster when you have a lot of tabs open (you can now search within all of your open tabs from the tab overflow menu).
  • Easier search via a redesigned new tab in Private Windows.
  • Smoother scrolling: Scroll anchoring keeps content from jumping as images and ads load at the top of the page.
  • Extensions now store their settings in a Firefox database, rather than individual JSON files, making every site you visit faster.
  • A redesigned keyboard shortcuts section in about:addons makes it easier to view and adjust default shortcuts.
  • Redesigned certificate error pages help you better understand and resolve issues, including identification of certificate issuers for anti-virus software.
  • Improved performance and reduced crash rates by doubling web content loading processes from 4 to 8.
  • Added basic support for macOS Touch Bar.
  • Experimenting with an improved Pocket experience in New Tab with different layouts and more topical content.
  • Easier, passwordless security: Added support for Windows Hello on Windows 10, allowing you to use your face, fingerprint, or external security keys for website authentication.
  • The Dark and Light Firefox themes now override the system setting for title bar accent color on Windows 10.
  • Linux users: Resolved an issue that caused Firefox to freeze when downloading files.
  • Various security fixes.
  • System title bar is hidden by default to match Gnome guideline for Linux users.
  • DevTools Inspector is now fully usable when the Debugger is paused.
  • Lowered priority of setTimeout and setInterval during page load to improve overall page load performance.
  • Fixed: button element is no longer special cased in event dispatch, per latest specifications.

If you’re a web developer, you’ll want to get more details here: Firefox 66 for developers.


This Firefox for Android release is worth getting for the same reasons as the desktop version: no more autoplaying sound and smoother scrolling. Additionally, you can now open files from external storage.

Here’s the full Firefox 66 for Android changelog:

  • Firefox now prevents websites from automatically playing sound by default.
  • Added support to open files from external storage, such as an SD card.
  • Smoother scrolling: Scroll anchoring keeps content from jumping as images and ads load at the top of the page.

Mozilla releases new Firefox versions every six to eight weeks, and Firefox 67 is currently slated for early May.

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