Experimental features in Firefox

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This page lists Firefox’s experimental and partially-implemented features, including evolving or proposed web platform standards. Each entry below includes information about the builds in which a feature is included (Nightly, Beta, Developer Edition, or Release), whether it is activated by default or not, and the name of the preference you can use to activate or configure the feature. The description of each feature also includes links to relevant Bugzilla bugs that implement or enable the feature. This information allows you to try out experimental features and provide feedback before they are officially released.

In terms of lifecycle, new features usually appear first in Nightly, where they are often enabled by default for early feedback and testing. If no major problems are found, they are included in Beta and Developer Edition pre-release builds. Finally, approved features ship in the stable Release channel. When a feature is enabled by default in a release, it is no longer considered experimental and is removed from this page.

To enable these features, enter about:config in the Firefox address bar, search for the associated preference and change its value, which is usually a toggle between true and false. Depending on the feature, you might need to restart the browser for the change to take effect. Check the Firefox Configuration Editor support article for more information about managing preferences in Firefox.

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.)

• layout.forms.input-type-search.enabled
  • : Set to true to enable.

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).

• layout.forms.reveal-password-button.enabled
  • : Set to true to enable.

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 hex box when they are not expected. (See Firefox bug 1099557 for more details.)

• layout.css.control-characters.visible
  • : Set to true to enable.

initial-letter property

The {{cssxref("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.)

• layout.css.initial-letter.enabled
  • : Set to true to enable.

fit-content() function

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

• layout.css.fit-content-function.enabled
  • : Set to true to enable.

Scroll-driven animations

Previously called “scroll-linked animations”, a scroll-driven animation depends on the scroll position of a scrollbar instead of time or some other dimension. The {{cssxref('scroll-timeline-name')}}  and {{cssxref('scroll-timeline-axis')}}  properties (and the {{cssxref('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 {{cssxref('animation-timeline')}}  property to the name value defined using scroll-timeline-name.

When using the {{cssxref('scroll-timeline')}}  shorthand property, the order of the property values must be {{cssxref('scroll-timeline-name')}}  followed by {{cssxref('scroll-timeline-axis')}} . The longhand and shorthand properties are both available behind the preference. You can alternatively use the scroll() functional notation with {{cssxref('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, Firefox bug 1817303, and Firefox bug 1737918.

The {{cssxref('timeline-scope')}} , {{cssxref('animation-range-start')}}  and {{cssxref('animation-range-end')}}  properties (and the {{cssxref('animation-range')}}  shorthand property) are not yet supported. For more information, see Firefox bug 1676779.

• layout.css.scroll-driven-animations.enabled
  • : Set to true to enable.

@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).

• layout.css.at-scope.enabled
  • : Set to true to enable.

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.

• layout.css.font-variant-emoji.enabled
  • : Set to true to enable.

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.

• layout.css.prefers-reduced-transparency.enabled
  • : Set to true to enable.

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.

• layout.css.inverted-colors.enabled
  • : Set to true to enable.

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.

• layout.css.scroll-driven-animations.enabled
  • : Set to true to enable.

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.

• layout.css.scroll-driven-animations.enabled
  • : Set to true to enable.

Vendor-prefixed transform properties

The -moz- prefixed CSS transform properties can be disabled by setting the layout.css.prefixes.transforms preference to false. The intent is to disable these once the standard CSS zoom properties are well supported. (Firefox bug 1886134, Firefox bug 1855763).

Specifically, this preference will disable the following prefixed properties:

• -moz-backface-visibility
• -moz-perspective
• -moz-perspective-origin
• -moz-transform
• -moz-transform-origin
• -moz-transform-style

• layout.css.prefixes.transforms
  • : Set to true to enable.

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: when set to false, it removes the UA styling for headings nested in sectioning elements. When set to true, it retains the existing UA styling for the nested headings.

• layout.css.h1-in-section-ua-styles.enabled
  • : Set to true to keep existing UA styles for nested headings.

shape() function

The CSS shape() function is a <basic-shape> data type that enables you to define a shape in the {{cssxref("clip-path")}}  and {{cssxref("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 {{cssxref("basic-shape/path","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.

• layout.css.basic-shape-shape.enabled
  • : Set to true to enable.

Symmetrical letter-spacing

The CSS {{cssxref("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.

• layout.css.letter-spacing.model
  • : Set to true to enable.

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.

• layout.css.relative-color-syntax.enabled
  • : Set to true to enable.

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 1838746).

The parts that have been implemented include CSSPositionTryRule and CSSPositionTryDescriptors (Firefox 131).

• layout.css.anchor-positioning.enabled
  • : Set to true to enable.

::details-content pseudo-element

The CSS {{cssxref("::details-content")}}  pseudo-element enables you to style the content of the {{htmlElement("details")}}  element (Firefox bug 1901037).

• layout.css.details-content.enabled
  • : Set to true to enable.

Allow pseudo-elements after element-backed pseudo-elements

Work has started on allowing pseudo-elements such as {{cssxref("::first-letter")}}  and {{cssxref("::before")}}  to be appended to element-backed pseudo-elements such as {{cssxref("::details-content")}}  and {{cssxref("::file-selector-button")}} .

This will allow users to, for , example, style the first letter of the {{htmlElement("details")}}  element by using the CSS selector ::details-content::first-letter or add content before an {{HTMLElement("input") }}  of type="file" using the CSS selector ::file-selector-button::before.

Currently only support for ::details-content::first-letter can be parsed, using @supports(::details-content::first-letter) and the preference for ::details-content pseudo-element needs enabling for this to be tested. The ::file-selector-button pseudo-element is not yet marked as an element-based pseudo-element so there is no current way of testing this. (Firefox bug 1953557).

• layout.css.details-content.enabled
  • : Set to true to enable.

SVG

No experimental features in this release cycle.

JavaScript

Atomics.waitAsync()

The {{jsxref("Atomics.waitAsync()")}}  static method waits asynchronously on a shared memory location and returns an object representing the result of the operation. It is non-blocking and usable on the main thread. (Firefox bug 1467846).

• javascript.options.atomics_wait_async
  • : Set to true to enable.

APIs

CloseWatcher Interface

Built-in web components with “open” and “close” semantics, such as modal dialogs and popovers, can be closed using device-native mechanisms. For example, on Android you can close a dialog using the back button. The {{domxref("CloseWatcher")}}  interface allows developers to implement UI components, such as custom sidebars, that can similarly be closed using native mechanisms. (Firefox bug 1888729).

• dom.closewatcher.enabled
  • : Set to true to enable.

Trusted Types API

The Trusted Types API provides mechanisms to ensure that functions that can potentially be used as vectors for XSS attacks are only able to be called with data that has been validated or sanitized.

[!NOTE] At the time of writing not enough of the API has been implemented for it to be effectively testable. This note will be removed once it is ready.

This subset of the API has been implemented:

• {{domxref("TrustedTypePolicyFactory")}} :
  • {{domxref("TrustedTypePolicyFactory/getAttributeType", "getAttributeType()")}}  and {{domxref("TrustedTypePolicyFactory/getPropertyType", "getPropertyType()")}}  (Firefox bug 1917783, Firefox bug 1917784).
• The {{domxref("Document.write()", "write()")}}  and {{domxref("Document.writeln()","writeln()")}}  methods of the {{domxref("Document")}}  interface now accept {{domxref("TrustedHTML")}}  objects as parameters, in addition to strings. (Firefox bug 1906301).
• The {{domxref("HTMLScriptElement.text","text")}} , {{domxref("HTMLElement.innerText","innerText")}} , and {{domxref("Node.textContent","textContent")}}  properties of the {{domxref("HTMLScriptElement")}}  interface now accept {{domxref("TrustedScript")}}  objects a value, while {{domxref("HTMLScriptElement.src", "src")}}  accepts {{domxref("TrustedScriptURL")}}  values. (Firefox bug 1905706).
• The {{domxref("Window.setInterval()")}}  and {{domxref("Window.setTimeout()")}}  methods can be called with a {{domxref("TrustedScript")}} . (Firefox bug 1931290).
• The global trustedTypes property is available for accessing the Trusted Types API.
• The properties {{domxref("Element.innerHTML")}}  and {{domxref("ShadowRoot.innerHTML")}}  can be called with trusted types.

• dom.security.trusted_types.enabled
  • : Set to true to enable.

HTML Sanitizer API

The HTML Sanitizer API allow developers to take untrusted strings of HTML and sanitize them for safe insertion into a document’s DOM.

• dom.security.sanitizer.enabled
  • : Set to true to enable.

closedBy attribute for <dialog>

The {{domxref("HTMLDialogElement/closedBy", "closedBy")}}  attribute of the {{domxref("HTMLDialogElement")}}  interface, and corresponding closedby attribute of the {{htmlelement("dialog")}}  element, are supported. These can be used by developers to specify whether users can close a dialog by clicking outside of the dialog area, or the dialog must be closed programmatically, and so on. (Firefox bug 1964077).

• dom.dialog.light-dismiss.enabled
  • : Set to true to enable.

Removal of MutationEvent

{{domxref("MutationEvent")}}  and its associated events (DOMSubtreeModified, DOMNodeInserted, DOMNodeRemoved, DOMCharacterDataModified, DOMAttrModified) are on the path for removal, and have been disabled on nightly. (Firefox bug 1951772).

• dom.mutation_events.enabled
  • : Set to true to enable.

Removal of beforescriptexecute and afterscriptexecute events

The non-standard events beforescriptexecute and afterscriptexecute on the {{domxref("Document")}}  interface, and afterscriptexecute and beforescriptexecute on the {{domxref("Element")}}  interface are on the path to removal. They have been disabled in Nightly. (Firefox bug 1954685).

• dom.events.script_execute.enable
  • : Set to true to enable.

PerformanceEventTiming.interactionId

{{domxref("PerformanceEventTiming.interactionId")}}  can be used to measure latency timing for events triggered by a particular user interaction. (Firefox bug 1934683).

• dom.performance.event_timing.enable_interactionid
  • : Set to true to enable.

Notification actions and maxActions properties

The {{domxref("Notification/actions","actions")}}  read-only property and the maxActions static read-only property of the {{domxref("Notification")}}  interface are supported in Nightly on desktop. These contain the notification actions set with {{domxref("ServiceWorkerRegistration.showNotification()")}} , and the maximum number of actions that can be set, respectively. (Firefox bug 1225110, Firefox bug 1963263).

• dom.webnotifications.actions.enabled
  • : Set to true to enable.

Graphics: Canvas, WebGL, and WebGPU

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.

• dom.webgpu.enabled
  • : Set to true to enable.

Reporting API support for CSP Violations

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

{{domxref('Report')}}  instances returned by the {{domxref('ReportingObserver')}}  interface can now have a type value of "csp-violation" and a body property that contains an instance of the {{domxref('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 {{CSP("report-to")}}  directive — endpoints names and corresponding URLs must first be defined in the {{httpheader('Reporting-Endpoints')}}  or {{httpheader('Report-To')}}  HTTP response headers. The report is a serialization of the {{domxref('Report')}}  object described above, with a body property that is a serialization of an {{domxref('CSPViolationReportBody')}}  instance.

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

• dom.reporting.enabled
  • : Set to true to enable.

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 {{domxref("SourceBuffer.appendBufferAsync", "appendBufferAsync()")}}  and {{domxref("SourceBuffer.removeAsync", "removeAsync()")}}  for adding and removing media source buffers to the {{domxref("SourceBuffer")}}  interface. See Firefox bug 1280613 and Firefox bug 778617 for more information.

• media.mediasource.experimental.enabled
  • : Set to true to enable.

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.

• image.avif.compliance_strictness
  • : Numeric value indicating a strictness level. Permitted values are:
    • 0: Permissive. Accept images with specification violations in both recommendations (“should” language) and requirements (“shall” language), provided they can be safely or unambiguously interpreted.
    • 1 (default): Mixed. Reject violations of requirements (“shall”), but allow violations of recommendations (“should”).
    • 2: Strict. Reject any violations of specified requirements or recommendations.

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).

• image.jxl.enabled
  • : Set to true to enable.

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.

• dom.vr.enabled
  • : Set to true to enable.

HTML DOM API

Selections crossing shadow DOM boundary

The {{domxref("Selection.getComposedRanges()")}}  method can be used to get an array of {{domxref("StaticRange")}}  objects representing the current selected range or ranges. Unlike {{domxref("Selection.getRangeAt()")}} , this method can return ranges with anchor or focus nodes inside a shadow DOM, but only if it is passed the {{domxref("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 {{domxref("Selection.setBaseAndExtent()","setBaseAndExtent()")}} , {{domxref("Selection.collapse()","collapse()")}} , and {{domxref("Selection.extend()","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).

• dom.shadowdom.selection_across_boundary.enabled
  • : Set to true to enable.

HTMLMediaElement properties: audioTracks and videoTracks

Enabling this feature adds the {{domxref("HTMLMediaElement.audioTracks")}}  and {{domxref("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.

• media.track.enabled
  • : Set to true to enable.

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

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

• layout.css.convertFromNode.enable
  • : Set to true to enable.

GeometryUtils method: getBoxQuads()

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

• layout.css.getBoxQuads.enabled
  • : Set to true to enable.

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.)

• dom.payments.request.enabled
  • : Set to true to enable.
• dom.payments.request.supportedRegions
  • : Country codes as a comma-separated allowlist of regions (e.g., US,CA).

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).

• dom.webshare.enabled
  • : Set to true to enable.

Screen Orientation API

ScreenOrientation.lock()

The {{domxref("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.

• dom.screenorientation.allow-lock
  • : Set to true to enable.

Prioritized Task Scheduling API

The Prioritized Task Scheduling API provides a standardized way to prioritize all tasks belonging to an application, whether they are defined in a website developer’s code, or in third-party libraries and frameworks. From Firefox version 140 the API is both feature complete and enabled in the Nightly release. (Firefox bug 1734997 and Firefox bug 1920115).

• dom.enable_web_task_scheduling
  • : Set to true to enable.

Notifications API

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

• dom.webnotifications.requireinteraction.enabled
  • : Set to true to enable.

View Transition API

The View Transition API provides a mechanism for easily creating animated transitions between different website views. This is especially useful for SPAs (single-page applications). (Firefox bug 1950759).

• dom.viewTransitions.enabled
  • : Set to true to enable.

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.

• security.mixed_content.block_object_subrequest
  • : Set to true to enable.

Insecure page labeling

The two security.insecure_connection_text_* 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 {{Glossary("HTTP")}}  rather than {{Glossary("HTTPS")}} ). The browser.urlbar.trimHttps preference trims the https: prefix from address bar URLs. See Firefox bug 1853418 for more details.

• security.insecure_connection_text.enabled
  • : Set to true to enable the text label for normal browsing mode.
• security.insecure_connection_text.pbmode.enabled
  • : Set to true to enable the text label for private browsing mode.
• browser.urlbar.trimHttps
  • : Set to true to trim the https: prefix from address bar URLs.

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.

• dom.security.featurePolicy.header.enabled
  • : Set to true to enable.

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 original explainer and the proposed spec. This experiment can be enabled for websites via origin trial or in the browser by setting the preference to 1. (Firefox bug 1900929).

• dom.origin-trials.private-attribution.state
  • : Set to true to enable.

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.

• image.jxl.enabled
  • : Set to true to enable.

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.

• network.cookie.sameSite.laxByDefault
  • : Set to true to enable.

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.

• network.cors_preflight.authorization_covered_by_wildcard
  • : Set to true to enable.

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.

No experimental features in this release cycle.

See also

• Firefox developer release notes
• Firefox Nightly
• Firefox Developer Edition