Firefox Developer Edition
Release Notes

Added support for WebAssembly, an emerging standard that brings near-native performance to Web-based games, apps, and software libraries without the use of plugins.

Added automatic captive portal detection, for easier access to Wi-Fi hotspots. When accessing the Internet via a captive portal, Firefox will alert users and open the portal login page in a new tab.

Enhanced Sync to allow users to send and open tabs from one device to another.

Enabled multi-process Firefox for 32-bit Windows users with touch screens

Added user warnings for non-secure HTTP pages with logins. Firefox now displays a “This connection is not secure” message when users click into the username and password fields on pages that don’t use HTTPS.

Implemented the Strict Secure Cookies specification which forbids insecure HTTP sites from setting cookies with the "secure" attribute. In some cases, this will prevent an insecure site from setting a cookie with the same name as an existing "secure" cookie from the same base domain.

Removed support for Netscape Plugin API (NPAPI) plugins other than Flash. Silverlight, Java, Acrobat and the like are no longer supported.

Removed Battery Status API to reduce fingerprinting of users by trackers

Redesigned Responsive Design Mode to include device selection, network throttling, and more

Improved security for screen sharing, which now shows a preview and no longer requires a whitelisted domain

Introduced the requestIdleCallback API

Introduced ECMAScript 7 async functions that makes it easier to write asynchronous code without chaining Promises

Touch events have been re-enabled on Windows desktop, which will help developers create a better user experience for people using a touchscreen.

Enabled CSS Grid Layout, opening up a world of new possibilities for graphic design

Introduced the selection events API