Download Firefox Developer Edition 129.0

New
- Added support for multiple languages in the same document spoken in macOS VoiceOver.
- Reader View has an enhanced Text and layout menu with new options for character spacing, word spacing, and text alignment. These changes offer users a more accessible reading experience.
Reader View now has a Theme menu with additional Contrast and Gray options. You can also select your own custom colors for text, background, and links from the Custom tab.
- Address Autofill enabled for users in France and Germany.
- HTTPS is replacing HTTP as the default protocol in the address bar on non-local sites. In case a site is not available via HTTPS, Firefox will fall back to HTTP.
Developer

Web Platform
- Added support for querying the encryption key system config in mediaCapabilities.decodingInfo() API.
- Added support for Float16Array typed arrays along with new DataView methods for reading and setting Float16 values, and a Math.f16round() static method that can be used to round numbers to 16 bits. The new type is useful for sharing data with a GPU, in particular for use cases where it makes sense to trade off precision for memory consumption.
- Added support for @starting-style. This at-rule allows to define styles that are applied to an element when it is first rendered, enabling transitions on elements that are added to the DOM or that have their display type changed from none to another value.
- Added support for the transition-behavior CSS property. This property allows us to create a transition on discrete animated CSS properties.
- Added support for textInput event, this is a non-standardized API and was replaced with beforeinput event. However, this is standardized and implemented for some web apps that use legacy libraries or frameworks. Please keep using beforeinput when developing new web apps.