Version 55.0a1, first offered to Nightly channel users on March 6, 2017
Firefox Nightly gets a new version every day and as a consequence, the release notes for the Nightly channel are updated continuously to reflect features that have reached sufficient maturity to benefit from community feedback and bug reports.
Features listed here may or may not make a final release of Firefox.
Launched Windows support for WebVR, bringing immersive experiences to the web. See examples and try working demos at Mozilla VR.
The Photon project aiming at refreshing the user interface started being implemented in Nightly. These changes are only visible on the nightly channel and will not land in the beta and release channels before at least version 57.
Modernized application update UI to be less intrusive and more aligned with the rest of the browser. Only users who have not restarted their browser 8 days after downloading an update or users who opted out of automatic updates will see this change.
Made the Adobe Flash plugin click-to-activate by default and allowed only on http:// and https:// URL schemes. (This change will not be visible to all users immediately. For more information see the Firefox plugin roadmap)