To give people a better Firefox experience, we’re changing the way plugins work. Earlier this year we talked about our plan for putting users in control of their plugins. We are now seeing these plans take shape in the latest version of Firefox Aurora. To give people more control over their browser, Firefox will no longer activate most plugins by default. When a site tries to use a plugin, the user will be able to choose whether to enable the plugin on that site.

A plugin is 3rd-party software which is loaded into the browser to assist in rendering the Web. Even though many users are not even aware of plugins, they are a significant source of hangs, crashes, and security incidents. By allowing users to decide which sites need to use plugins, Firefox will help protect them and keep their browser running smoothly.

The one plugin not affected by this change is Flash, which will remain enabled by default. Flash content is so common on the Web, and many websites use “hidden” Flash instances that the user does not see and cannot click on: making Flash click-to-play would be confusing for most users. Users with older versions of Flash that are known to be insecure will see the click-to-activate UI and will be prompted to upgrade to the latest version. Our security and plugin teams work closely with Adobe to make sure that Firefox users are protected from instability or security issues in the Flash plugin.

When Mozilla conducted a user research study on the prototype implementation of click-to-play plugins earlier this year, we discovered that many users did not understand what a plugin was. Participants were confused or annoyed by the experience, especially having to enable plugins on the same site repeatedly. We redesigned the click-to-play feature to focus on enabling plugins per-site, rather than enabling individual plugin instances on the page. Advanced users who want to activate individual instances may still do so by installing a Firefox extension. We encourage people who want to try the new plugin experience to use the Mozilla Nightly or Aurora preview releases.

Plugins used to be an important tool for prototyping and implementing new features such as video and animation. As browsers have advanced, this kind of feature development can occur directly within the browser using technologies such as WebGL, WebSockets, WebRTC, and asm.js. Mozilla projects such as pdf.js and Shumway demonstrate that plugins can be implemented within the Web platform.

Plugins are now a legacy technology, and not available on most mobile devices. Mozilla encourages website developers to avoid using plugins wherever possible. If there are plugin features which are not available in the web platform, we encourage developers to post their use cases to mozilla.dev.platform project list, so that Mozilla can prioritize web platform work to make those use cases possible.

– Benjamin Smedberg, Engineering Manager, Stability and Plugins