For Developers‎ > ‎

Web Platform Status


Last updated: March 6, 2013
DevRel Contact: Eric Bidelman (ericbidelman), Paul Irish (paulirish)

This page captures the implementation status of HTML5 feature support in Chrome (desktop) and Chrome for Android. The current release of Chrome for Android matches m25, any exceptions to this will be indicated below.

You have a few ways to watch these features more closely: 
Many of these features have their own jumpoff point on, with links to solid tutorials and resources.
The near-daily-updated Chrome Canary lands these features much sooner than the stable or beta releases. (Though it's pre-alpha, so expect bugs!)

Note: In this page there are many references to "m6" and such. This refers to the stable Chrome release of that version. 

File APIs

Handle file uploads and file manipulation.
Availability: Basic File API support in m5.
Spec: w3c spec
Notes: Limited form of drag-and-drop available in Firefox 3.6

File System

Availability: started to land in m8, but only available for apps & extensions. Synchronous APIs are in m9 for web workers.  window.resolveLocalFileSystemURL() and Entry.toURL() were added in m11.  Stable release for web pages [not apps/extensions] was m13. 
Spec: w3c spec
Notes: devtools support coming. Needs flag --allow-file-access-from-files for testing from file:// URLs.
Demos: layouttests
Dev Contact: Eric Uhrhane (ericu)

Drag and Drop Directories

Allows dragging and dropping entire folders using HTML5 Drag and Drop. Extends the DataTransferItem with a method to get a FileEntry/DirectoryEntry.
(var entry = DataTransferItem.webkitGetAsEntry())
Availability: M21
Dev Contact: Kinuko Yasuda (kinuko)


Get FileSystem API entries representing user selected files from an <input type="file" multiple>.
Dev Contact: Kinuko Yasuda (kinuko)


Availability: basic in m8, sync api in m9 for web workers
Spec: w3c spec 
Dev Contact: Eric Uhrhane (ericu)


Can read local and parse local files.
Availability: m7.
Spec: w3c spec
Demo: demo
Dev Contact: Jian Li (jianli)


Build blobs (files).
Availability: m8. As of m20, this API is deprecated. Use Blob() constructor instead (see below).
Demo: demo
Spec: w3c spec
Notes: window.createBlobURL() changed to new spec's window.createObjectURL() somewhere around m8. As of M10, the call is prefixed under window.webkitURL.createObjectURL(). Chrome 23 unprefixes window.URL.

Blob() constructor

Removes the need for BlobBuilder API. Allows you to construct Blobs directly (var blob = new Blob(["1234"], {type: 'text/plain'}))
Availability: M20
Spec: w3c spec

Blob() constructor ArrayBufferView support

Blob() constructor takes ArrayBufferView directly rather than constructing a blob with ArrayBuffer.
Availability: M21

Unprefixed Blob.slice() support

Blob.slice() is un-prefixed (from webkitSlice()) in M21.
Availability: M22

Typed Arrays

Buffers for holding binary data and working with WebGL & Audio API: ArrayBufferFloat32Array , Int16Array, Uint8Array, etc.) 
Availability: m7 for most. DataView is m9. Float64Array in m13. 
Spec: Khronos
Notes: worker.postMessage(TypedArray|ArrayBuffer) landed in m13 using structured cloning. postMesage(Object|Array) (e.g. any type) landed in M23.

a[download] attribute

When used on an <a>, this attribute signifies that the resource it points to should be downloaded by the browser rather than navigating to it. 
Availability: M14
Spec: whatwg
Demo: demo

Offline and XHR

App Cache

Enables web pages to work without the user being connected to the internet

Notes: Chrome's implementation is maxed at 260MB. Individual files max out at 32MB (260MB/8)
Availability: m5. Dev tools support added in m6
Dev Contact: Michael Nordman (michaeln)

XHR supports xhr.send(ArrayBuffer)

Allows for sending a binary byte array using xhr.
Availability: targeting m9
Dev Contact: Jian Li (jianli)
Spec: w3 draft

XHR supports xhr.send(Blob|File)

Allows for sending a Blob or File using xhr.
Availability: m7
Spec: w3 draft
Dev Contact:  Eric Uhrhane (ericu)

XHR supports xhr.send(FormData)

Availability: landed m6

XHR supports xhr.send(ArrayBufferView)

Allows for sending a typed array directly rather than sending just its ArrayBuffer.
Availability: m22

XHR.response, XHR.responseType

Allows reading an xhr response as a blob/arraybuffer (xhr.responseType = 'arraybuffer', xhr.responseType = 'blob')

Availability: m10. m18 adds xhr.responseType = 'document' (see HTML in XMLHttpRequest) and
restricts the usage of synchronous XHRs (, false);)  by throwing an error when .responseType is set.
Spec: w3 draft
Tickets: (arraybuffer works, blob does not)
Dev Contact: Michael Nordman (michaeln)


Availability: m7
Spec: w3 draft


Access the underlying network information (connection info) of the device.

Availability: target unknown
Spec: w3 draft
Notes: In Android since 2.2, but not implemented yet desktop browsers.
Dev Contact: -


Allows an application to check if the user has an active internet connection. Also can register 'online' and 'offline' event handlers. 

Availability: m14
Dev Contact: adamk


Allow web applications to handle URL protocols like mailto:.
Availability: m13
Notes: Protocol list: "mailto", "mms", "nntp", "rtsp", "webcal". Custom protocols require "web+" prefix (e.g. "web+myScheme").
           There are no plans to implement registerContentHandler.
Dev Contact: koz

Directory upload

Allow specifying a directory to upload (<input type="file" multiple webkitdirectory />), which is just be an extension of existing form mime-multipart file upload.
Availability: m8. m21 landed dragging and dropping a folder onto an <input type="file" webkidirectory> element).
Demo: demo


Spec: W3C editor's draft
Protocol Spec: RFC 6455 + x-webkit-deflate-frame
Demo: demo
Planned: Implement permessage-compress extension and mux extension
Dev Contact: tyoshino

Strict Transport Security

Header to inform the browser to always request a given domain over SSL, reducing MITM attack surface area.
Availability: m4
Spec: ietf spec

a[ping] attribute.

Notify resource on link click. 
Availability: Chrome 7. 
Notes: webkit changeset. Can be disabled through a command line flag or in about:flags


Web SQL Database

API exposing an SQLite database 
Availability: m4.
Notes: No spec progress or other implementations (outside of Webkit/Opera) expected.
Demo: demo
Dev Contact: Dumitru Daniliuc (dumi)

Availability: Indeterminate status

Indexed Database API  

Availability: Landed in m11. (Prefixed as webkitIndexedDB pre M24.)
Spec: Draft w3c spec
Notes: formerly called WebSimpleDB. 
Dev Contacts: dgrogan, jsbell, alecflett

Cross-Browser Status:
  • Firefox: FF16+ enabled (through 4beta9 as moz_indexedDB; through FF15 as mozIndexedDB)
  • IE: IE10+ (IE10 Platform Preview through 5 as msIndexedDB)
    • IE10 will not support Array key paths
  • Opera implementation is in progress
Known differences between Chrome (as of M25and the draft specification (as of July 16, 2012):
  • a "blocked" event will fire against a request created by an open(name, version), a setVersion(version) or deleteDatabase(name) call even if all other connections are closed in response to a "versionchange" event
  • "blocked" events may also fire multiple times against the same deleteDatabase(name) request
  • Blobs, Files, and FileLists in values are not supported.
  • The Sync API is not supported - but neither IE nor Firefox support this either; it is marked as "At Risk" in the spec
Updates in M23 (from M22)
  • The new-style open(name, version).onupgradeneeded API is now supported; the old open(name) followed by setVersion(version) API may still be used for now, but web applications should migrate as soon as possible.
Updates in M22 (from M21)
  • deleteDatabase() and webkitGetDatabaseNames() can now be called from Workers
  • IDBKeyRange.upperOpen/lowerOpen flags are now reported correctly when lowerBound()/upperBound() used
  • Empty arrays are no longer valid key paths
  • Requests can no longer be issued against transactions when not active (i.e. outside of creation context or callbacks, e.g. from a timeout or non-IDB event)
  • "versionchange" events are no longer fired against connections that are closing
  • Multi-entry indexes with invalid/duplicate subkeys now populated per spec
Updates in M21 (from M20)

Web Storage

Availability: localStorage in m4, sessionStorage in m5
Notes: localStorage serves basic use cases. For more comprehensive storage solution, consider IndexedDB. While the spec indicates anything that structured clone algorithm can clone can be stored, all browser implementations currently allow only strings. Chrome's storage capacity is currently 2.5mb.
Dev Contact: Jeremy Orlow (jorlow) -> Michael Nordman (michaeln)

Quota Management API

This API can be used to check how much quota an app/origin is using.

Availability: m13: FileSystem (TEMPORARY & PERSISTENT) and WebSQL (temp only). m14 : AppCache and IndexedDB were added (TEMP only)
Dev Contact: Kinuko Yasuda (kinuko)

CSS & Presentation

CSS3 3D Transforms

Availability:  m12
Spec: w3 spec
Notes: Associated GPU rendering quirkiness actively being worked on in prep for beta channel release.

new semantic sectioning elements

sectionarticleasidenavheader, and footer elements
Availability: m5

<progress> and <meter> elements

Offer a visual display of progress. 
Availability: m6
Spec: whatwg spec 


Ruby annotations are short runs of text presented alongside base text, primarily used in East Asian typography as a guide for pronunciation or to include other annotations
Availability: m4
Notes: description & demo on whatwg blog

@font-face webfonts

Availability: OTF/TTF support in m4. WOFF in m6. 
Notes: unicode-range support planned. Improved handling of text while font asset is being downloaded, also planned.


Availability: w3c linear-gradient() syntax as of m10. original webkit -gradient() syntax as of m3.
Notes: The legacy syntax will be retained for the foreseeable future.

Background printing

Opt-in ability to specify a background should be printed
Availability: landing in m16 with prefix: -webkit-print-background

Scoped style sheets

Boolean attribute for the <style> element (<style scoped>). When present, its styles only apply to the parent element.

Availability: m20  (enable webkit experimental feature in about:flags)
Spec: whatwg
Demo: jsbin

CSS3 Filters

Apply (SVG-like) filter effects to arbitrary DOM elements.

Availability:  m19
Spec: w3 spec

CSS Shaders

Apply OpenGL shaders to arbitrary DOM elements.

Availability:  m24, enabled via about:flags.
Spec: w3 spec

CSS3 Grid Layout

Availability: work is just started behind a flag. No way to enable it.
Spec: w3c
Dev Contact: Tony Chang (tony@chromium), Ojan Vafai (ojan@chromium)

CSS3 Flexbox Model (the new one)

Note: The old box model (display: -webkit-box) and spec has been replaced by a new one (display: -webkit-flex).
For now, chrome supports both. But you should use the new one!

Availability:  started landing in m18. m21 has the latest and full implementation with a bunch of properties renamed.
Spec: w3 spec
Dev Contact: Ojan Vafai (ojan)

CSS3 Regions

Magazine-like content flow into specified regions.

Availability:  Partial support in m19  (enable webkit experimental feature in about:flags)
Spec: w3c

position: sticky

position: sticky is a new way to position elements and is conceptually similar to position: fixed. The difference is that a stickily positioned element behaves like position: relative within its parent, until a given offset threshold is met.

Availability:  M23 (enable webkit experimental feature in about:flags)
Proposal: www-style

CSS Intrinsic Sizing

width: fill-available, width: min-content, width: max-content, etc.

Availability:  ~M22 (vendor prefixed)
Spec: w3c

Other CSS3

box-shadow: inset keyword and spread value supported since m4, went unprefixed in m10
border-radius: went unprefixed in m4
cross-fade(): landing with prefix (-webkit-cross-fade) in m17. demo
image-resolution()landed for m21 spec
clip-path: landed for m24. Prefixed -webkit-clip-path. spec
@viewport: spec, bug
@supports: spec, bug, 
CSS viewport % lengths (vw, vh, vmin, vmax): spec, Availability: m20



Provides an API to draw 2D graphics 
Availability: m1, Safari, Firefox, Opera, IE9
Notes: Accelerated 2D canvas targeting m14 for windows/linux; perhaps m15 for mac. Currently, available in about:flags.
webp format: canvas.toDataURL("image/webp") added in m17 (WebKit 535), but m18 on Mac.
In M20, canvas.getImageData(...).data returns a  Uint8ClampedArray instead of a CanvasPixelArray.

WebGL  (Canvas 3D)

3D rendering via the <canvas> element. 
Availability: m9
Android Availability: TBD.
Notes: Originally project developed by Mozilla as a JavaScript API to make OpenGL calls - WebGL Wiki
Dev Contact: Vangelis Kokevis (vangelis), Ken Russell (kbr)


Offload animation repainting to browser for optimized performance. 
Availability: m10 , currently prefixed as window.webkitRequestAnimationFrame
Notes: As of FF4, Mozilla's implementation differs and offers lower framerates, but it will be addressed. This method should be used for WebGL, Canvas 2D, and DOM/CSS animation.
Dev Contact: jamesr

Accelerated Video: m10
WebP image format support: m9. alpha and lossless added to m22.


Video and Audio

Natively play video and audio in the browser
Provides API and built-in playback controls
Availability: m3. Also Safari 4, Firefox 3.5
Codecs: mp4, ogv, and webm ship with Chrome. webm shipped in m6.
Dev Contact: Andrew Scherkus (scherkus)

mediaElem.webkitAudioDecodedByteCount - m11
mediaElem.webkitVideoDecodedByteCount - m11
videoElem.webkitDecodedFrameCount - m11
videoElem.webkitDroppedFrameCount - m11

Web Audio API

Availability: dev channel since m12. stable channel in m14. m24 adds the ability for live mic input (enable in about:flags). m25 updated API calls to the latest spec.
Android availability: TBD (issue 166003)
Notes: enable via about:flags. Also, Mozilla has an alternative Audio Data API proposal. M20 included
support for oscillator nodes.
Dev Contact: Chris Rogers (crogers)

Media Source API

Allows appending data to an <audio>/<video> element.

Availability: dev channel m23
Spec: w3c spec
Notes: enable via about:flags or run with --enable-media-source flag.
Dev Contact: Aaron Colwell (acolwell)


Real time communication in the browser. (Note that many online resources refer to 'WebRTC' but just mean getUserMedia!)

Combines the following APIs: 
- navigator.getUserMedia (aka MediaStream, cross-browser demo:
- RTCPeerConnection (demos:,
- RTCDataChannel (demo

- M21 for getUserMedia (prefixed), 
- M23 for RTCPeerConnection (prefixed and flagless from M23)
- M26 for RTCDataChannel (prefixed, flagless), requires an RTCPeerConnection { optional:[ { RtpDataChannels: true } ]} constraint and only supports unreliable data channels and text messages.

Spec: w3c spec

- webkitRTCPeerConnection is the name for RTCPeerConnection implementation currently in Chrome: other names/implementations are obsolete; prefix will be removed when APIs stabilise
- for the permission dialog: Chrome only show the "Always allow" for sites using https, for increased security
- getUserMedia is implemented in Opera and Firefox Stable (video only), and Chrome and Firefox Nightly/Aurora (audio and video); 
- RTCPeerConnection and RTCDataChannel are implemented in Firefox Aurora/Nightly
- getUserMedia can be used as input to Web Audio (demo, the implementation can be enabled in about:flags)
- Chrome <=> Firefox RTCPeerConnection interop demo (blog)

Resolution Constraints are enabled as of M24: 
 - demo
Tab Capture (i.e. ability to get stream of 'screencast') currently available in Chrome Dev channel:

Screen Capture (i.e. ability to capture the contents of the screen) currently available in Chrome 26.0.1410.0:

Code samples: web-rtc samples on
Dev contact: Serge Lachapelle (sergel) 

Track element

Add subtitles, captions, screen reader descriptions, chapters and other types of timed metadata to video and audio. Chrome currently supports the WebVTT format for track data.

Availability: m23
Specs: WHATWG, W3C, WebVTT
Notes: Rendering does not yet include CSS pseudo elements.
Dev Contact: Andrew Scherkus (scherkus), Silvia Pfeiffer (silviapf)

Encrypted Media Extensions

Enables playback of encrypted streams in an <audio>/<video> elements.

Availability: m25: WebM Encryption & ISO BMFF Common Encryption (CENC)
Spec: W3C Editor's Draft: v0.1b (m22 and later); latest (object-oriented version not yet implemented)
Notes: In m25, enable via about:flags or run with --enable-encrypted-media flag. (Enabled by default in m26 and later on desktop and Chrome OS.)
Dev Contact: David Dorwin (ddorwin)

JS Web Speech API

Enables web developers to incorporate speech recognition and synthesis into their web pages.

Availability: m25
Spec: w3c
Dev Contact: gshires

Web Components

Shadow DOM

Availability: m18 exposed WebKitShadowRoot().Enable Shadow DOM in about:flags.  DevTools support is in m20, behind the DevTools Experiments flag (and setting). m25 removes constructor and exposes element.webkitCreateShadowRoot() by default.
Notes: As of m13, elements internally ported to the shadow dom: <progress>, <meter>, <video>, <input type=range>, <keygen>. 
Dev Contact: dglazkov


HTML template element to allow creating fragment of inert HTML as a prototype for stamping out DOM.

Spec: w3c
Availability: targeting m26
Dev Contact: rafaelw


Method for registering (creating) custom elements in script.

Availability: bug

CSS @host at-rule

Allows styling of the element hosting shadow dom.

Spec: spec
Demo: demo
Availability: m25

CSS ::distributed() pseudo element

Allows styling of nodes distributed into an insertion point.

Spec: spec
Demo: demo
Availability: m26

Other Open Web Platform features

Desktop notifications

Availability: m5
Notes: Additional functionality added in m6: in-place replacement of notifications, BiDi support, Worker support, and UI improvement.
           In M22, createHTMLNotification() was removed because of spec compliance. See this post
Dev Contact: John Gregg (johnnyg) 


Interactive widget to show/hide content.

Availability: m12


Predefined data/options for controls

Spec: W3C
Availability: m20. See update for mor info.


The dialog element represents a part of an application that a user interacts with to perform a task, for example a dialog box, inspector, or window.

Availability: Behind a flag in m25. Enable "Experimental WebKit Features" in about:flags.
Dev contact: falken

Device Orientation

Enables real-time events about the 3 dimensional orientation of the device/laptop
Availability: m7, in Intel-based Apple portables ( kb), iOS 4.2+
Demo: demo


Also called Server-sent Events, these are push notifications from the server received as DOM events.
Availability: m6

Fullscreen API

Programmatically instruct content on the page to be presented in the browser's full screen (kiosk) mode.
Availability: m15
Spec: w3c spec
Dev contact: jeremya


The pushState, replaceState, and clearState methods provide applications with programmatic control over session history. 
Availability: m5. history.state was implemented in m18. popstate firing after page load:
Documentation: MDN


Enables websites to get geolocation information from browsers 
Availability: m5, also Firefox 3.5
Dev Contact: Andrei Popescu (andreip) 

GamePad API

Gives JS access to a game controller via USB.
Availability: targeting m18
Spec: W3C Editor's draft  
Dev contact: scottmg
Notes: Chromium tracking issue. Enabled in about:flags

Battery Status

Allows access to see the battery level of the device's battery
Availability: unknown
Demo: here

DOM MutationObservers

Provides notifications when DOM nodes are rearranged or modified.
Availability: m18, prefixed as WebKitMutationObserver; unprefixed in current Firefox
Related links:
Useful library: Mutation Summary
Dev Contact: rafaelw

<iframe> attributes

The seamless attribute is used to embed and <iframe> in the calling page without scrollbars or borders (e.g. seamlessly). In m26, seamless iframes inherit styles from their embedding parent page.
Availability: m20 
Spec: whatwg

Gives the content of an iframe as a src context to embed (e.g. <iframe seamless srcdoc="<b>Hello World</b>"></iframe>).
Note: If both src and srcdoc are set, the latter takes precedence.
Availability: m20
Spec: whatwg

Method of running external site pages with reduced privileges (i.e. no JavaScript) in iframes (<iframe sandbox="allow-same-origin allow-forms" src="..."></iframe>)
Availability: m19
Spec: whatwg


API for testing if a given media query will apply.
Availability: m9

Pointer Lock (TAPIFKA Mouse Lock)

Gives access to raw mouse movement, locks the target of mouse events to a single element, eliminates limits of how far mouse movement can go in a single direction, and removes the cursor from view. Obvious use cases are for first person or real time strategy games.
Availability: m18 behind flag. On be default in m22 with a refined API similar to requestFullScreen.
Documentation: HTML5 Rocks
Dev contact: scheib

Note, late breaking changes:
Pointer lock can only work within one document. If you lock in one iframe, you can not have another iframe try to lock and transfer the target... it will error instead. The first iframe has to unlock, then the second iframe can lock.

Also, iframes work by default, but sandboxed iframes block pointer lock. Landed recently into WebKit the ability to use <iframe sandbox="allow-pointer-lock">, but that will not percolate into Chrome until 23.

Page Visibility

Provides an API to ask whether the current tab is visibile or not. If you, you might want to throttle back action or set an idle state.
Availability: m13, prefixed as document.webkitHidden
Notes: Relatedly, setTimeout/Interval are clamped to 1000ms when in a background tab as of m11. Firefox 5 has the same behavior.
Dev Contact: shishir


Provides a threading API
Availability: Chrome 3, Safari 4, Firefox 3.5. Shared workers available in m4.
Android Availability: Dedicated workers in m16 (0.16). No shared workers, yet.
Notes: Pre-M15, there was a limit to the number of workers that each page can start, as well as the number of workers that can be running globally across all pages. This was because a new process was started for each worker. As of M15, workers are started in-process, meaning  less memory footprint and faster messaging. Transferrable objects landed in  m17 (see next)
Dev Contact: Dmitry Lomov (dslomov), Drew Wilson (atwilson)

Transferable Object messaging passing

With transferable objects/data, ownership is transferred from one context to another. It is zero-copy, which vastly improves the performance of sending data to a Worker or another window.
Availability: m17
Spec: w3c spec
Notes: landed as prefixed. Unprefixed in M24.
worker.postMessage(arrayBuffer, [arrayBuffer])
window.postMessage(arrayBuffer, targetOrigin, [arrayBuffer])

<link> load/error events

Specify and onload or onerror event for a stylesheet to load.
Availability: m19?
Spec: W3C

Touch Events

Android Availability: m16 (0.16)


Availability: m24
Spec: w3c spec

JS Internationalization API

Allows collation (string comparison), number formatting, and date and time formatting for JavaScript applications. More info here.
Availability: m24
Spec: here

Resource Timing API

Availability: m25
Spec: w3c

User Timing API

Availability: m25
Spec: w3c

Way to observe changes to JS objects.
Availability: m25 (behind Enable Experimental JS Features in about:flags)


Availability: See HTML5 Forms Status for all details. (Updated as recently as Nov 28th, 2012).
Includes details in input types (like date and color), input attributes, datalist and more. 


Provides hints to the autofill implementation to allow Chrome to better provide suggested values to the user.
Availability: The x-autocompletetype attribute was implemented in Chrome 15. It used token values that are documented here, but later revised. Chrome 24 features an implementation of the autocomplete attribute that matches the HTML spec.


Element.outerHTML - m1
Element.textContent (faster than innerHTML for plain text) - m1
Element.classList (classList.add/remove methods) - m8
Element.dataset (Provides easy access to data-* attribute values) - m8

window.onerror event - m10
crypto.getRandomValues() - m11
selectionchange event - m11

Chrome  Extensions

More resources for going deep with HTML5:

Subpages (1): HTML5 Forms Status