Experimental features in Firefox

This page lists Firefox's experimental and partially implemented features, including those for proposed or cutting-edge web platform standards, along with information on the builds in which they are present, whether or not they are activated "by default", and which preference can be used to activate or deactivate them. This allows you to test the features before they are released.

New features appear first in the Firefox Nightly build, where they are often enabled by default. They later propagate though to Firefox Developer Edition and eventually to the release build. After a feature is enabled by default in a release build, it is no longer considered experimental and should be removed from the topic.

Experimental features can be enabled or disabled using the Firefox Configuration Editor (enter about:config in the Firefox address bar) by modifying the associated preference listed below.

Note: For editors - when adding features to these tables, please try to include a link to the relevant bug or bugs using [Firefox bug <number>](https://bugzil.la/<number>).

HTML

Layout for input type="search"

Layout for input type="search" has been updated. This causes a search field to have a clear icon once someone starts typing in it, to match other browser implementations. (See Firefox bug 558594 for more details.)

Release channel Version added Enabled by default?
Nightly 81 No
Developer Edition 81 No
Beta 81 No
Release 81 No
Preference name layout.forms.input-type-search.enabled

Toggle password display

HTML password input elements (<input type="password">) include an "eye" icon that can be toggled to display or obscure the password text (Firefox bug 502258).

Release channel Version added Enabled by default?
Nightly 96 No
Developer Edition 96 No
Beta 96 No
Release 96 No
Preference name layout.forms.reveal-password-button.enabled

CSS

Hex boxes to display stray control characters

This feature renders control characters (Unicode category Cc) other than tab (U+0009), line feed (U+000A), form feed (U+000C), and carriage return (U+000D) as a hexbox when they are not expected. (See Firefox bug 1099557 for more details.)

Release channel Version added Enabled by default?
Nightly 43 Yes
Developer Edition 43 No
Beta 43 No
Release 43 No
Preference name layout.css.control-characters.enabled or layout.css.control-characters.visible

initial-letter property

The initial-letter CSS property is part of the CSS Inline Layout specification and allows you to specify how dropped, raised, and sunken initial letters are displayed. (See Firefox bug 1223880 for more details.)

Release channel Version added Enabled by default?
Nightly 50 No
Developer Edition 50 No
Beta 50 No
Release 50 No
Preference name layout.css.initial-letter.enabled

from keyword for relative colors

The from keyword is now parsed as valid CSS syntax when the layout.css.relative-color-syntax.enabled preference is set to true. Although this keyword currently has no effect, it will not produce syntax errors when used in valid places in CSS color functions, thereby supporting the ongoing work on relative colors. See Firefox bug 1889133 for more details.

Release channel Version added Enabled by default?
Nightly 126 No
Developer Edition 126 No
Beta 126 No
Release 126 No
Preference name layout.css.relative-color-syntax.enabled

Single numbers as aspect ratio in media queries

Support for using a single <number> as a <ratio> when specifying the aspect ratio for a media query. (See Firefox bug 1565562 for more details.)

Release channel Version added Enabled by default?
Nightly 70 No
Developer Edition 70 No
Beta 70 No
Release 70 No
Preference name layout.css.aspect-ratio-number.enabled

backdrop-filter property

The backdrop-filter property applies filter effects to the area behind an element. (See Firefox bug 1178765 for more details.)

Release channel Version added Enabled by default?
Nightly 70 No
Developer Edition 70 No
Beta 70 No
Release 70 No
Preference name layout.css.backdrop-filter.enabled

fit-content() function

The fit-content() function as it applies to width and other sizing properties. This function is already well-supported for CSS Grid Layout track sizing. (See Firefox bug 1312588 for more details.)

Release channel Version added Enabled by default?
Nightly 91 No
Developer Edition 91 No
Beta 91 No
Release 91 No
Preference name layout.css.fit-content-function.enabled

Scroll-driven animations

Earlier called "scroll-linked animations", a scroll-driven animation depends on the scroll position of a scrollbar instead of time or some other dimension. The scroll-timeline-name and scroll-timeline-axis properties (and the scroll-timeline shorthand property) allow you to specify that a particular scrollbar in a particular named container can be used as the source for a scroll-driven animation. The scroll timeline can then be associated with an animation by setting the animation-timeline property to the name value defined using scroll-timeline-name.

When using the scroll-timeline shorthand property, the order of the property values must be scroll-timeline-name followed by scroll-timeline-axis. The longhand and shorthand properties are both available behind the preference.

You can alternatively use the scroll() functional notation with animation-timeline to indicate that a scrollbar axis in an ancestor element will be used for the timeline.

For more information, see Firefox bug 1807685, Firefox bug 1804573, Firefox bug 1809005, Firefox bug 1676791, Firefox bug 1754897, and Firefox bug 1737918.

Release channel Version added Enabled by default?
Nightly 110 No
Developer Edition 110 No
Beta 110 No
Release 110 No
Preference name layout.css.scroll-driven-animations.enabled

@scope at-rule

The @scope CSS at-rule allows you to select specific child elements without having to overly increase the specificity of CSS selectors (Firefox bug 1886441).

Release channel Version added Enabled by default?
Nightly 128 No
Developer Edition 128 No
Beta 128 No
Release 128 No
Preference name layout.css.at-scope.enabled

@font-face src feature checking

The @font-face src descriptor now supports the tech() function, allowing fallback of whether a font resource is downloaded based on whether the user-agent supports a particular font feature or technology. See Firefox bug 1715546 for more details.

Release channel Version added Enabled by default?
Nightly 105 Yes
Developer Edition 105 No
Beta 105 No
Release 105 No
Preference name layout.css.font-tech.enabled

font-variant-emoji property

The CSS font-variant-emoji property allows you to set a default presentation style for displaying emojis. See (Firefox bug 1461589) for more details.

Release channel Version added Enabled by default?
Nightly 108 Yes
Developer Edition 108 No
Beta 108 No
Release 108 No
Preference name layout.css.font-variant-emoji.enabled

page-orientation descriptor

The page-orientation CSS descriptor for the @page at-rule controls the rotation of a printed page. It handles the flow of content across pages when the orientation of a page is changed. This behavior differs from the size descriptor in that a user can define the direction in which to rotate the page. See (Firefox bug 1673987) for more details.

Release channel Version added Enabled by default?
Nightly 111 Yes
Developer Edition 111 No
Beta 111 No
Release 111 No
Preference name layout.css.page-orientation.enabled

prefers-reduced-transparency media feature

The CSS prefers-reduced-transparency media feature lets you detect if a user has enabled the setting to minimize the amount of transparent or translucent layer effects on their device. See (Firefox bug 1736914) for more details.

Release channel Version added Enabled by default?
Nightly 113 No
Developer Edition 113 No
Beta 113 No
Release 113 No
Preference name layout.css.prefers-reduced-transparency.enabled

inverted-colors media feature

The CSS inverted-colors media feature lets you detect if a user agent or the underlying operating system is inverting colors. See (Firefox bug 1794628) for more details.

Release channel Version added Enabled by default?
Nightly 114 No
Developer Edition 114 No
Beta 114 No
Release 114 No
Preference name layout.css.inverted-colors.enabled

Named view progress timelines property

The CSS view-timeline-name property lets you give a name to particular element, identifying that its ancestor scroller element is the source of a view progress timeline. The name can then be assigned to the animation-timeline, which then animates the associated element as it moves through the visible area of its ancestor scroller. See (Firefox bug 1737920) for more details.

Release channel Version added Enabled by default?
Nightly 114 No
Developer Edition 114 No
Beta 114 No
Release 114 No
Preference name layout.css.scroll-driven-animations.enabled

Anonymous view progress timelines function

The CSS view() function lets you specify that the animation-timeline for an element is a view progress timeline, which will animate the element as it moves through the visible area of its ancestor scroller. The function defines the axis of the parent element that supplies the timeline, along with the inset within the visible area at which the animation starts and begins. See (Firefox bug 1808410) for more details.

Release channel Version added Enabled by default?
Nightly 114 No
Developer Edition 114 No
Beta 114 No
Release 114 No
Preference name layout.css.scroll-driven-animations.enabled

zoom property

The non-standard CSS zoom property is enabled in the Nightly release and lets you magnify an element similar to the transform property, but it affects the layout size of the element. See (Firefox bug 1855763 and Firefox bug 390936) for more details.

Release channel Version added Enabled by default?
Nightly 120 Yes
Developer Edition 120 No
Beta 120 No
Release 120 No
Preference name layout.css.zoom.enabled

To ensure compatibility with these changes, the Vendor-prefixed transform properties and the Vendor-prefixed transition properties are disabled in the Nightly release. These changes are described in the following sections.

text-wrap: balance & stable values

The text-wrap CSS property values balance and stable allow the layout of short content to be wrapped in a balanced manner and for editable content to not reflow while the user is editing it, respectively. (See Firefox bug 1731541 for more details.)

Release channel Version added Enabled by default?
Nightly 120 Yes
Developer Edition 120 No
Beta 120 No
Release 120 No
Preference name layout.css.text-wrap-balance.enabled, layout.css.text-wrap-balance.limit, layout.css.text-wrap-balance-after-clamp.enabled

Vendor-prefixed transform properties

The -moz- prefixed CSS transform properties have been disabled in the Nightly release via the layout.css.prefixes.transforms preference being set to false. (Firefox bug 1855763). Specifically, the disabled properties are:

  • -moz-backface-visibility
  • -moz-perspective
  • -moz-perspective-origin
  • -moz-transform
  • -moz-transform-origin
  • -moz-transform-style
Release channel Version added Enabled by default?
Nightly 120 No
Developer Edition 120 Yes
Beta 120 Yes
Release 120 Yes
Preference name layout.css.prefixes.transforms

Vendor-prefixed transition properties

The -moz- prefixed CSS transitions properties have been disabled in the Nightly release via the layout.css.prefixes.transitions preference being set to false. (Firefox bug 1855763). Specifically, the disabled properties are:

  • -moz-transition
  • -moz-transition-delay
  • -moz-transition-duration
  • -moz-transition-property
  • -moz-transition-timing-function
Release channel Version added Enabled by default?
Nightly 120 No
Developer Edition 120 Yes
Beta 120 Yes
Release 120 Yes
Preference name layout.css.prefixes.transitions

UA styles for <h1> nested in sectioning elements

The <h1> heading doesn't decrease in font size now when nested within sectioning elements <article>, <aside>, <nav>, and <section>. The UA styles for <h1> nested within sectioning elements are no longer relevant since the outline algorithm has been removed from the HTML specification. (Firefox bug 1883896).

Note: The preference for this feature works in reverse: it's set to false in the Nightly build, which removes the UA styling for headings nested in sectioning elements. It's set to true in all other channels, which retains the existing UA styling for the nested headings.

Release channel Version added Enabled by default?
Nightly 125 No
Developer Edition 125 Yes
Beta 125 Yes
Release 125 Yes
Preference name layout.css.h1-in-section-ua-styles.enabled

shape() function

The CSS shape() function is a <basic-shape> data type that enables you to define a shape in the clip-path and offset-path properties using one or more "shape commands". These commands are very similar to the SVG path commands. The shape() function is similar in some respects to the path() function, but unlike path(), which uses the SVG path syntax, shape() uses standard CSS syntax. This enables you to easily create and edit shapes and also allows the use of CSS math functions. For more details, see Firefox bug 1823463 for the shape() function support in clip-path, Firefox bug 1884424 for the function's support in offset-path, and Firefox bug 1884425 for its interpolation support.

Release channel Version added Enabled by default?
Nightly 126 Yes
Developer Edition 126 No
Beta 126 No
Release 126 No
Preference name layout.css.basic-shape-shape.enabled

@starting-style at-rule

The CSS @starting-style at-rule allows you to set the starting styles of an element for a CSS transition, when the element has no default initial style. This is particularly useful for elements that are hidden from view on the first paint such as popover or 'dialog'. Does not yet support animating from display: none. For more details, see Firefox bug 1834876 and Firefox bug 1834877.

Release channel Version added Enabled by default?
Nightly 127 Yes
Developer Edition 127 No
Beta 127 No
Release 127 No
Preference name layout.css.starting-style-at-rules.enabled

Symmetrical letter-spacing

The CSS letter-spacing property now splits the specified letter spacing evenly on both sides of each character. This is unlike the current behavior where spacing is added primarily to one side. This approach can improve text spacing, especially in mixed-directional text Firefox bug 1891446.

Release channel Version added Enabled by default?
Nightly 128 Yes
Developer Edition 127 No
Beta 127 No
Release 127 No
Preference name layout.css.letter-spacing.model

calc() color channel support in relative colors

The CSS calc() function can now parse color channels in relative colors, allowing you to correctly calculate changes to colors in different color spaces or while using different functional notations Firefox bug 1889561.

Release channel Version added Enabled by default?
Nightly 127 Yes
Developer Edition 127 No
Beta 127 No
Release 127 No
Preference name layout.css.relative-color-syntax.enabled

CSS Anchor Positioning

The CSS Anchor Positioning module defines a number of features that allow elements to be defined as anchor elements, and for other elements to be positioned relative to anchor elements. This allows, for example, tooltips to be displayed alongside associated content as it scrolls through the viewport, moving as needed when it would overflow the viewport, and disappearing when the anchor moves offscreen. The set of features are being progressively rolled out behind a preference (Firefox bug 1889561).

The parts that have been implemented include:

Release channel Version added Enabled by default?
Nightly 131 No
Developer Edition 131 No
Beta 131 No
Release 131 No
Preference name layout.css.anchor-positioning.enabled

SVG

SVGPathSeg APIs

The SVGPathSeg APIs are being unshipped, and have been placed behind a preference. This includes: SVGPathSegList, SVGPathElement.getPathSegAtLength(), SVGAnimatedPathData. (See Firefox bug 1388931 for more details.)

Release channel Version removed Enabled by default?
Nightly 97 No
Developer Edition 97 No
Beta 97 No
Release 97 No
Preference name dom.svg.pathSeg.enabled

JavaScript

Regular expression (?ims-ims:...) modifiers

The (?ims-ims:...) regular expression modifiers allow you to make changes to only take effect in a specific part of a regex pattern.

Release channel Version added Enabled by default?
Nightly 131 No
Developer Edition - -
Beta - -
Release - -
Preference name javascript.options.experimental.regexp_modifiers

APIs

Graphics: Canvas, WebGL, and WebGPU

Request video frame callbacks

The requestVideoFrameCallback() method of the HTMLVideoElement interface registers a callback function that runs when a new video frame is sent to the compositor. Developers can use this to perform operations on each video frame, enabling more efficient painting to a canvas, video analysis, synchronization with external audio sources, and so on. The method returns a callback handle that can be passed to HTMLVideoElement.cancelVideoFrameCallback() in order to cancel the outstanding callback request. (Firefox bug 1800882).

Release channel Version added Enabled by default?
Nightly 130 Yes
Developer Edition 130 No
Beta 130 No
Release 130 No
Preference name media.rvfc.enabled

Hit regions

Whether the mouse coordinates are within a particular area on the canvas is a common problem to solve. The hit region API allows you to define an area of your canvas and provides another possibility to expose interactive content on a canvas to accessibility tools.

Release channel Version added Enabled by default?
Nightly 30 No
Developer Edition 30 No
Beta 30 No
Release 30 No
Preference name canvas.hitregions.enabled

WebGL: Draft extensions

When this preference is enabled, any WebGL extensions currently in "draft" status which are being tested are enabled for use. Currently, there are no WebGL extensions being tested by Firefox.

WebGPU API

The WebGPU API provides low-level support for performing computation and graphics rendering using the Graphics Processing Unit (GPU) of the user's device or computer. See Firefox bug 1602129 for our progress on this API.

Release channel Version added Enabled by default?
Nightly 113 Yes
Developer Edition 73 No
Beta 73 No
Release 73 No
Preference name dom.webgpu.enabled

Reporting API support for CSP Violations

The Reporting API now has support for reporting Content Security Policy (CSP) violations.

Report instances returned by the ReportingObserver interface can now have a type value of "csp-violation" and a body property that contains an instance of the CSPViolationReportBody interface. This allows CSP violations to be reported within a web page.

CSP violation reports can also be sent to remote endpoints that are specified by name in the CSP report-to directive — endpoints names and corresponding URLs must first be defined in the Reporting-Endpoints or Report-To HTTP response headers. The report is a serialization of the Report object described above, with a body property that is a serialization of an CSPViolationReportBody instance.

This violation report replaces a similar CSP-specific mechanism for sending violation reports, which uses the CSP report-uri directive to set the URL of the reporting endpoint, and has a CSP-specific JSON violation report format. (Firefox bug 1391243).

Release channel Version added Enabled by default?
Nightly 130 No
Developer Edition 130 No
Beta 130 No
Release 130 No
Preference name dom.reporting.enabled

WebRTC and media

The following experimental features include those found in the WebRTC API, the Web Audio API, the Media Source Extensions API, the Encrypted Media Extensions API, and the Media Capture and Streams API.

Asynchronous SourceBuffer add and remove

This adds the promise-based methods appendBufferAsync() and removeAsync() for adding and removing media source buffers to the SourceBuffer interface. See Firefox bug 1280613 and Firefox bug 778617 for more information.

Release channel Version added Enabled by default?
Nightly 62 No
Developer Edition 62 No
Beta 62 No
Release 62 No
Preference name media.mediasource.experimental.enabled

AVIF compliance strictness

The image.avif.compliance_strictness preference can be used to control the strictness applied when processing AVIF images. This allows Firefox users to display images that render on some other browsers, even if they are not strictly compliant.

Permitted values are:

  • 0: Accept images with specification violations in both recommendations ("should" language) and requirements ("shall" language), provided they can be safely or unambiguously interpreted.
  • 1 (default): Reject violations of requirements, but allow violations of recommendations.
  • 2: Strict. Reject any violations in requirements or recommendations.
Release channel Version added Default value
Nightly 92 1
Developer Edition 92 1
Beta 92 1
Release 92 1
Preference name image.avif.compliance_strictness

JPEG XL support

Firefox supports JPEG XL images if this feature is enabled. See Firefox bug 1539075 for more details.

Note that, as shown below, the feature is only available on Nightly builds (irrespective of whether the preference is set).

Release channel Version added Enabled by default?
Nightly 90 No
Developer Edition
Beta
Release
Preference name image.jxl.enabled

OpenFont COLRv1 fonts

This feature provides support for the OpenFont COLRv1 font specification. This enables compression-friendly color vector fonts with gradients, compositing and blending to be loaded using the CSS @font-face rule, or the CSS Font Loading API. See Firefox bug 1740530 for more details.

Release channel Version added Enabled by default?
Nightly 105 No
Developer Edition 105 No
Beta 105 No
Release 105 No
Preference name gfx.font_rendering.colr_v1.enabled

CSS Custom Highlight API

The CSS Custom Highlight API provides a mechanism for styling arbitrary text ranges in a document (generalizing the behavior of other highlight pseudo-elements such as ::selection, ::spelling-error, ::grammar-error, and ::target-text). The ranges are defined in JavaScript using Range instances grouped in a Highlight, and then registered with a name using HighlightRegistry. The CSS ::highlight pseudo-element is used to apply styles to a registered highlight. See Firefox bug 1703961 for more details.

Release channel Version added Enabled by default?
Nightly 117 Yes
Developer Edition 117 No
Beta 117 No
Release 117 No
Preference name dom.customHighlightAPI.enabled

Service Workers

Preloading of service worker resources on navigation

The NavigationPreloadManager interface can be used to enable preloading of resources when navigating to a page. Preloading occurs in parallel with worker bootup, reducing the total time from start of navigation until resources are fetched.

Release channel Version added Enabled by default?
Nightly 99 yes
Developer Edition 97 No
Beta 97 No
Release 97 No
Preference name dom.serviceWorkers.navigationPreload.enabled

WebVR API

WebVR API (Disabled)

The deprecated WebVR API is on the path for removal. It is disabled by default on all builds Firefox bug 1750902.

Release channel Version removed Enabled by default?
Nightly 98 No
Developer Edition 98 No
Beta 98 No
Release 98 No
Preference name dom.vr.enabled

HTML DOM API

Selections crossing shadow DOM boundary

The Selection.getComposedRanges() method can be used to get an array of StaticRange objects representing the current selected range or ranges. Unlike Selection.getRangeAt(), this method can return ranges with anchor or focus nodes inside a shadow DOM, but only if it is passed the ShadowRoot objects that contain those nodes. Otherwise, it will return a range that has been re-scoped to include the host node of the shadow root that contains the node. The Selection methods setBaseAndExtent(), collapse(), and extend() have also been modified to accept nodes inside a shadow root.

User selection via mouse, keyboard, and so on, can start and end anywhere in the document, including inside any open or closed shadow trees. (Firefox bug 1867058).

Release channel Version added Enabled by default?
Nightly 126 Yes
Developer Edition 126 No
Beta 126 No
Release 126 No
Preference name dom.shadowdom.selection_across_boundary.enabled

HTMLMediaElement method: setSinkId()

HTMLMediaElement.setSinkId() allows you to set the sink ID of an audio output device on an HTMLMediaElement, thereby changing where the audio is being output. See Firefox bug 934425 for more details.

Release channel Version added Enabled by default?
Nightly 64 No
Developer Edition 64 No
Beta 64 No
Release 64 No
Preference name media.setsinkid.enabled

HTMLMediaElement properties: audioTracks and videoTracks

Enabling this feature adds the HTMLMediaElement.audioTracks and HTMLMediaElement.videoTracks properties to all HTML media elements. However, because Firefox doesn't currently support multiple audio and video tracks, the most common use cases for these properties don't work, so they're both disabled by default. See Firefox bug 1057233 for more details.

Release channel Version added Enabled by default?
Nightly 33 No
Developer Edition 33 No
Beta 33 No
Release 33 No
Preference name media.track.enabled

GeometryUtils methods: convertPointFromNode(), convertRectFromNode(), and convertQuadFromNode()

The GeometryUtils methods convertPointFromNode(), convertRectFromNode(), and convertQuadFromNode() map the given point, rectangle, or quadruple from the Node on which they're called to another node. (See Firefox bug 918189 for more details.)

Release channel Version added Enabled by default?
Nightly 31 Yes
Developer Edition 31 No
Beta 31 No
Release 31 No
Preference name layout.css.convertFromNode.enable

GeometryUtils method: getBoxQuads()

The GeometryUtils method getBoxQuads() returns the CSS boxes for a Node relative to any other node or viewport. (See Firefox bug 917755 for more details.)

Release channel Version added Enabled by default?
Nightly 31 Yes
Developer Edition 31 No
Beta 31 No
Release 31 No
Preference name layout.css.getBoxQuads.enabled

Payment Request API

Primary payment handling

The Payment Request API provides support for handling web-based payments within web content or apps. Due to a bug that came up during testing of the user interface, we have decided to postpone shipping this API while discussions over potential changes to the API are held. Work is ongoing. (See Firefox bug 1318984 for more details.)

Release channel Version added Enabled by default?
Nightly 55 No
Developer Edition 55 No
Beta 55 No
Release 55 No
Preference name dom.payments.request.enabled and
dom.payments.request.supportedRegions

WebShare API

The Web Share API allows sharing of files, URLs and other data from a site. This feature is enabled on Android in all builds, but behind a preference on Desktop (unless specified below).

Release channel Version changed Enabled by default?
Nightly 71 No (default). Yes (Windows from version 92)
Developer Edition 71 No
Beta 71 No
Release 71 No (Desktop). Yes (Android).
Preference name dom.webshare.enabled

Screen Orientation API

ScreenOrientation.lock()

The ScreenOrientation.lock() method allows a device to be locked to a particular orientation, if supported by the device and allowed by browser pre-lock requirements. Typically locking the orientation is only allowed on mobile devices when the document is being displayed full screen. See Firefox bug 1697647 for more details.

Release channel Version changed Enabled by default?
Nightly 111 Yes
Developer Edition 97 No
Beta 97 No
Release 97 No
Preference name dom.screenorientation.allow-lock

Prioritized Task Scheduling API

The Prioritized Task Scheduling API provides a standardized way to prioritize all tasks belonging to an application, whether they defined in a website developer's code, or in third party libraries and frameworks.

This is enabled on Firefox Nightly (only) from Firefox 101. No preference is provided to allow it to be enabled in other releases.

Notifications API

Notifications have the requireInteraction property set to true by default on Windows systems and in the Nightly release (Firefox bug 1794475).

Release channel Version changed Enabled by default?
Nightly 117 Yes
Developer Edition 117 No
Beta 117 No
Release 117 Windows only
Preference name dom.webnotifications.requireinteraction.enabled

Security and privacy

Block plain text requests from Flash on encrypted pages

In order to help mitigate man-in-the-middle (MitM) attacks caused by Flash content on encrypted pages, a preference has been added to treat OBJECT_SUBREQUESTs as active content. See Firefox bug 1190623 for more details.

Release channel Version added Enabled by default?
Nightly 59 No
Developer Edition 59 No
Beta 59 No
Release 59 No
Preference name security.mixed_content.block_object_subrequest

Insecure page labeling

These two preferences add a "Not secure" text label in the address bar next to the traditional lock icon when a page is loaded insecurely (that is, using HTTP rather than HTTPS). See Firefox bug 1335970 for more details.

Release channel Version added Enabled by default?
Nightly 60 No
Developer Edition 60 No
Beta 60 No
Release 60 No
Preference name security.insecure_connection_text.enabled for normal browsing mode; security.insecure_connection_text.pbmode.enabled for private browsing mode

Permissions Policy / Feature policy

Permissions Policy allows web developers to selectively enable, disable, and modify the behavior of certain features and APIs in the browser. It is similar to CSP but controls features instead of security behavior. This is implemented in Firefox as Feature Policy, the name used in an earlier version of the specification.

Note that supported policies can be set through the allow attribute on <iframe> elements even if the user preference is not set.

Release channel Version added Enabled by default?
Nightly 65 No
Developer Edition 65 No
Beta 65 No
Release 65 No
Preference name dom.security.featurePolicy.header.enabled

Permissions API support for microphone and camera

The Permissions API permissions microphone and camera are supported, allowing a web page to query whether access to the corresponding hardware has been granted, denied, or still requires user approval (Firefox bug 1609427, Firefox bug 1915222).

Release channel Version added Enabled by default?
Nightly 131 Yes
Developer Edition 131 Yes
Beta 131 Yes
Release 131 No
Preference name permissions.media.query.enabled

Clear-Site-Data "cache" directive

The Clear-Site-Data HTTP response header cache directive clears the browser cache for the requesting website.

Note: This was originally enabled by default, but put behind a preference in version 94 (Firefox bug 1729291).

Release channel Version added Enabled by default?
Nightly 63 No
Developer Edition 63 No
Beta 63 No
Release 63 No
Preference name privacy.clearsitedata.cache.enabled

Privacy Preserving Attribution API (PPA)

PPA API provides an alternative to user tracking for ad attribution using the new navigator.privateAttribution object with saveImpression() and measureConversion() methods. Read more about PPA in the explainer. This experiment can be enabled for websites via origin trial or in the browser by setting the preference to 1. (Firefox bug 1900929).

Release channel Version added Enabled by default?
Nightly 128 No
Developer Edition 128 No
Beta 128 No
Release 128 No
Preference name dom.origin-trials.private-attribution.state

HTTP

Accept header with MIME type image/jxl

The HTTP Accept header in default requests and image requests can be configured via a preference to indicate support for the image/jxl MIME type.

Release channel Version added Enabled by default?
Nightly 128 No
Developer Edition 128 No
Beta 128 No
Release 128 No
Preference name image.jxl.enabled

SameSite=Lax by default

SameSite cookies have a default value of Lax. With this setting, cookies are only sent when a user is navigating to the origin site, not for cross-site subrequests to load images or frames into a third party site and so on. For more details see Firefox bug 1617609.

Release channel Version added Enabled by default?
Nightly 69 No
Developer Edition 69 No
Beta 69 No
Release 69 No
Preference name network.cookie.sameSite.laxByDefault

Access-Control-Allow-Headers wildcard does not cover Authorization

The Access-Control-Allow-Headers is a response header to a CORS preflight request, that indicates which request headers may be included in the final request. The response directive can contain a wildcard (*), which indicates that the final request may include all headers except the Authorization header.

By default, Firefox includes the Authorization header in the final request after receiving a response with Access-Control-Allow-Headers: *. Set the preference to false to ensure Firefox does not include the Authorization header. For more details see Firefox bug 1687364.

Release channel Version added Enabled by default?
Nightly 115 Yes
Developer Edition 115 Yes
Beta 115 Yes
Release 115 Yes
Preference name network.cors_preflight.authorization_covered_by_wildcard

Developer tools

Mozilla's developer tools are constantly evolving. We experiment with new ideas, add new features, and test them on the Nightly and Developer Edition channels before letting them go through to beta and release. The features below are the current crop of experimental developer tool features.

Execution context selector

This feature displays a button on the console's command line that lets you change the context in which the expression you enter will be executed. (See Firefox bug 1605154 and Firefox bug 1605153 for more details.)

Release channel Version added Enabled by default?
Nightly 75 No
Developer Edition 75 No
Beta 75 No
Release 75 No
Preference name devtools.webconsole.input.context

Mobile gesture support in Responsive Design Mode

Mouse gestures are used to simulate mobile gestures like swiping/scrolling, double-tap and pinch-zooming and long-press to select/open the context menu. (See Firefox bug 1621781, Firefox bug 1245183, and Firefox bug 1401304 for more details.)

Release channel Version added Enabled by default?
Nightly 76[1] Yes
Developer Edition 76[1] Yes
Beta 76[1] Yes
Release 76[1] No
Preference name n/a

[1] Support for zooming using the double-tap gesture was added in Firefox 76. The other gestures were added for Firefox 79.

Server-sent events in Network Monitor

The Network Monitor displays information for server-sent events. (See Firefox bug 1405706 for more details.)

Release channel Version added Enabled by default?
Nightly 80 Yes
Developer Edition 80 Yes
Beta 80 No
Release 80 No
Preference name devtools.netmonitor.features.serverSentEvents

CSS browser compatibility tooltips

The CSS Rules View can display browser compatibility tooltips next to any CSS properties that have known issues. For more information see: Examine and edit HTML > Browser Compat Warnings.

Release channel Version added Enabled by default?
Nightly 81 No
Developer Edition 81 No
Beta 81 No
Release 81 No
Preference name devtools.inspector.ruleview.inline-compatibility-warning.enabled

UI

Desktop zooming

This feature lets you enable smooth pinch zooming on desktop computers without requiring layout reflows, just like mobile devices do. (See Firefox bug 1245183 and Firefox bug 1620055 for more details.)

Release channel Version added Enabled by default?
Nightly 42 Yes
Developer Edition 42 No
Beta 42 No
Release 42 No
Preference name apz.allow_zooming and (on Windows) apz.windows.use_direct_manipulation

See also