Not yet stable

For a given set of browsers, what APIs are not yet in all of them.

Example Comparisons
Browsers
Features

Summary

A count of the number of APIs are in Browser X but not in Browser Y.
Not in ChromeNot in FirefoxNot in Safari
In Chrome 106123
In Firefox 928
In Safari 35

Unstable APIs

Below is a list of features that are not in all of Chrome, Firefox, and Safari

Raw Data

Quick Links:

HTTP Data

API First Browser Date Days in Limbo Notes
http.headers.Accept-CH 📋Chrome10/13/20153989
http.headers.Accept-CH.Content-DPR Chrome10/13/20153989
http.headers.Accept-CH.DPR Chrome10/13/20153989
http.headers.Accept-CH.Device-Memory Chrome9/5/20173296
http.headers.Accept-CH.Sec-CH-UA Chrome3/2/20212022
http.headers.Accept-CH.Sec-CH-UA-Arch Chrome3/2/20212022
http.headers.Accept-CH.Sec-CH-UA-Full-Version Chrome3/2/20212022
http.headers.Accept-CH.Sec-CH-UA-Mobile Chrome3/2/20212022
http.headers.Accept-CH.Sec-CH-UA-Model Chrome3/2/20212022
http.headers.Accept-CH.Sec-CH-UA-Platform Chrome3/2/20212022
http.headers.Accept-CH.Sec-CH-UA-Platform-Version Chrome3/2/20212022
http.headers.Accept-CH.Viewport-Width Chrome10/13/20153989
http.headers.Accept-CH.Width Chrome10/13/20153989
http.headers.Access-Control-Allow-Headers.authorization_not_covered_by_wildcard Firefox7/4/20231168
http.headers.Attribution-Reporting-Eligible 📋Chrome9/12/20231098
http.headers.Attribution-Reporting-Register-Source 📋Chrome9/12/20231098
http.headers.Attribution-Reporting-Register-Trigger 📋Chrome9/12/20231098
http.headers.Attribution-Reporting-Support 📋Chrome9/12/20231098
http.headers.Authorization.Digest.SHA-256 Firefox10/5/20211805
http.headers.Authorization.authorization_removed_cross_origin 📋Safari10/24/20221421
http.headers.Cache-Control.immutable Firefox9/20/20163646
http.headers.Clear-Site-Data.cache 📋Chrome9/5/20173296
http.headers.Clear-Site-Data.clientHints 📋Chrome9/12/20231098
http.headers.Content-DPR Chrome10/13/20153989
http.headers.Content-Encoding.zstd 📋Chrome3/19/2024909
http.headers.Content-Security-Policy.block-all-mixed-content Chrome7/21/20154073
Chrome: Will be removed, see bug 40260100.Chrome Android: Will be removed, see bug 40260100.Quest Browser: Will be removed, see bug 40260100.Opera: Will be removed, see bug 40260100.Opera Android: Will be removed, see bug 40260100.Samsung Internet: Will be removed, see bug 40260100.WebView Android: Will be removed, see bug 40260100.
http.headers.Content-Security-Policy.fenced-frame-src 📋Chrome7/18/20231154
http.headers.Content-Security-Policy.form-action.blocks_redirects Chrome12/6/20173204
http.headers.Content-Security-Policy.prefetch-src Safari1/23/20231330
http.headers.Content-Security-Policy.require-trusted-types-for 📋Chrome5/19/20202309
http.headers.Content-Security-Policy.script-src.inline-speculation-rules 📋Chrome2/7/20231315
http.headers.Content-Security-Policy.trusted-types 📋Chrome5/19/20202309
http.headers.Critical-CH 📋Chrome5/25/20211938
http.headers.Cross-Origin-Embedder-Policy.credentialless 📋Chrome11/15/20211764
http.headers.Cross-Origin-Opener-Policy.noopener-allow-popups 📋Chrome11/12/2024671
http.headers.DNT Firefox3/22/20115655
http.headers.DPR Chrome10/13/20153989
http.headers.Device-Memory 📋Chrome9/5/20173296
http.headers.Downlink 📋Chrome5/29/20183030
Chrome: The value is never greater than 10 Mbps, as a non-standard anti-fingerprinting measure.Chrome Android: The value is never greater than 10 Mbps, as a non-standard anti-fingerprinting measure.Edge: The value is never greater than 10 Mbps, as a non-standard anti-fingerprinting measure.Quest Browser: The value is never greater than 10 Mbps, as a non-standard anti-fingerprinting measure.Opera: The value is never greater than 10 Mbps, as a non-standard anti-fingerprinting measure.Opera Android: The value is never greater than 10 Mbps, as a non-standard anti-fingerprinting measure.Samsung Internet: The value is never greater than 10 Mbps, as a non-standard anti-fingerprinting measure.WebView Android: The value is never greater than 10 Mbps, as a non-standard anti-fingerprinting measure.
http.headers.ECT 📋Chrome5/29/20183030
http.headers.Early-Data 📋Firefox1/23/20183156
http.headers.Expect-CT 📋Chrome9/5/20173296
Chrome: Before later builds of Chrome 64, invalid Expect-CT reports would be sent. Newer versions do not send reports after 10 weeks from the build date. See bug 41356303.Chrome Android: Before later builds of Chrome Android 64, invalid Expect-CT reports would be sent. Newer versions do not send reports after 10 weeks from the build date. See bug 41356303.Quest Browser: Before later builds of Quest Browser 5.0, invalid Expect-CT reports would be sent. Newer versions do not send reports after 10 weeks from the build date. See bug 41356303.Opera Android: Before later builds of Opera Android 47, invalid Expect-CT reports would be sent. Newer versions do not send reports after 10 weeks from the build date. See bug 41356303.Samsung Internet: Before later builds of Samsung Internet 9.0, invalid Expect-CT reports would be sent. Newer versions do not send reports after 10 weeks from the build date. See bug 41356303.
http.headers.Link.blocking 📋Chrome9/2/20221473
http.headers.Link.expect 📋Chrome4/16/2024881
http.headers.NEL 📋Chrome12/4/20182841
http.headers.No-Vary-Search 📋Chrome7/23/2024783
Chrome: Supported for navigation prefetch cache only.Chrome Android: Supported for navigation prefetch cache only.Edge: Supported for navigation prefetch cache only.Opera: Supported for navigation prefetch cache only.Opera Android: Supported for navigation prefetch cache only.Samsung Internet: Supported for navigation prefetch cache only.WebView Android: Supported for navigation prefetch cache only.
http.headers.Observe-Browsing-Topics Chrome7/18/20231154
http.headers.Origin-Agent-Cluster 📋Chrome4/13/20211980
http.headers.Permissions-Policy 📋Chrome1/19/20212064
http.headers.Permissions-Policy.accelerometer 📋Chrome4/17/20183072
http.headers.Permissions-Policy.ambient-light-sensor 📋Chrome4/17/20183072
http.headers.Permissions-Policy.attribution-reporting 📋Chrome9/12/20231098
http.headers.Permissions-Policy.autoplay 📋Chrome1/23/20183156
http.headers.Permissions-Policy.bluetooth 📋Chrome8/2/20221504
http.headers.Permissions-Policy.browsing-topics Chrome7/18/20231154
http.headers.Permissions-Policy.camera 📋Chrome1/23/20183156
http.headers.Permissions-Policy.compute-pressure 📋Chrome5/14/2024853
http.headers.Permissions-Policy.cross-origin-isolated 📋Chrome11/17/20202127
http.headers.Permissions-Policy.display-capture 📋Chrome9/21/20211819
http.headers.Permissions-Policy.document-domain 📋Chrome1/23/20183156
http.headers.Permissions-Policy.encrypted-media 📋Chrome1/23/20183156
http.headers.Permissions-Policy.fullscreen 📋Chrome10/17/20173254
http.headers.Permissions-Policy.geolocation 📋Chrome1/23/20183156
http.headers.Permissions-Policy.gyroscope 📋Chrome4/17/20183072
http.headers.Permissions-Policy.hid 📋Chrome3/2/20212022
http.headers.Permissions-Policy.identity-credentials-get 📋Chrome2/7/20231315
http.headers.Permissions-Policy.idle-detection 📋Chrome9/21/20211819
http.headers.Permissions-Policy.local-fonts 📋Chrome6/21/20221546
http.headers.Permissions-Policy.magnetometer 📋Chrome4/17/20183072
http.headers.Permissions-Policy.microphone 📋Chrome1/23/20183156
http.headers.Permissions-Policy.midi 📋Chrome1/23/20183156
http.headers.Permissions-Policy.otp-credentials 📋Chrome8/31/20211840
http.headers.Permissions-Policy.payment 📋Chrome7/25/20173338
http.headers.Permissions-Policy.picture-in-picture 📋Chrome12/4/20182841
http.headers.Permissions-Policy.publickey-credentials-create 📋Chrome7/27/20202240
http.headers.Permissions-Policy.publickey-credentials-get 📋Chrome7/27/20202240
http.headers.Permissions-Policy.screen-wake-lock 📋Chrome7/27/20202240
http.headers.Permissions-Policy.serial 📋Chrome3/2/20212022
http.headers.Permissions-Policy.storage-access 📋Chrome5/2/20231231
http.headers.Permissions-Policy.usb 📋Chrome7/25/20173338
http.headers.Permissions-Policy.web-share 📋Chrome10/20/20202155
http.headers.Permissions-Policy.wildcards Chrome11/29/20221385
http.headers.Permissions-Policy.window-management 📋Chrome3/29/20221630
http.headers.Permissions-Policy.xr-spatial-tracking 📋Chrome12/10/20192470
http.headers.Priority 📋Chrome4/16/2024881
http.headers.RTT 📋Chrome5/29/20183030
Chrome: The value is never greater than 3000 ms, as a non-standard anti-fingerprinting measure.Chrome Android: The value is never greater than 3000 ms, as a non-standard anti-fingerprinting measure.Edge: The value is never greater than 3000 ms, as a non-standard anti-fingerprinting measure.Quest Browser: The value is never greater than 3000 ms, as a non-standard anti-fingerprinting measure.Opera: The value is never greater than 3000 ms, as a non-standard anti-fingerprinting measure.Opera Android: The value is never greater than 3000 ms, as a non-standard anti-fingerprinting measure.Samsung Internet: The value is never greater than 3000 ms, as a non-standard anti-fingerprinting measure.WebView Android: The value is never greater than 3000 ms, as a non-standard anti-fingerprinting measure.
http.headers.Referrer-Policy.no-referrer-when-downgrade Chrome1/25/20173519
http.headers.Referrer-Policy.origin-when-cross-origin Chrome1/25/20173519
http.headers.Referrer-Policy.unsafe-url Chrome1/25/20173519
http.headers.Report-To Chrome10/16/20182890
http.headers.Reporting-Endpoints 📋Chrome11/15/20211764
http.headers.Retry-After 📋Chrome1/10/20134995
http.headers.Save-Data 📋Chrome3/2/20163848
http.headers.Sec-Browsing-Topics Chrome7/18/20231154
http.headers.Sec-CH-Prefers-Color-Scheme 📋Chrome8/31/20211840
http.headers.Sec-CH-Prefers-Reduced-Motion 📋Chrome11/29/20221385
http.headers.Sec-CH-Prefers-Reduced-Transparency 📋Chrome10/31/20231049
http.headers.Sec-CH-UA 📋Chrome3/2/20212022
http.headers.Sec-CH-UA-Arch 📋Chrome3/2/20212022
http.headers.Sec-CH-UA-Bitness 📋Chrome8/31/20211840
http.headers.Sec-CH-UA-Full-Version 📋Chrome3/2/20212022
http.headers.Sec-CH-UA-Full-Version-List 📋Chrome2/1/20221686
http.headers.Sec-CH-UA-Mobile 📋Chrome3/2/20212022
http.headers.Sec-CH-UA-Model 📋Chrome3/2/20212022
http.headers.Sec-CH-UA-Platform 📋Chrome3/2/20212022
http.headers.Sec-CH-UA-Platform-Version 📋Chrome3/2/20212022
http.headers.Sec-Fetch-Dest.fencedframe Chrome7/18/20231154
http.headers.Sec-GPC 📋Firefox11/21/20231028
Firefox: Opt-in to GPC using the Website Privacy Preference setting (about:preferences#privacy) checkbox 'Tell websites not to sell or share my data', or by setting the preference privacy.globalprivacycontrol.enabled to true.
http.headers.Sec-Purpose 📋Chrome2/7/20231315
http.headers.Sec-Purpose.prefetch Firefox7/4/20231168
Chrome: Doesn't support Sec-Purpose for <link rel="prefetch">. In Chrome, the legacy Purpose: prefetch header is used to indicate a link request is a prefetch. See bug 40236973.Chrome Android: Doesn't support Sec-Purpose for <link rel="prefetch">. In Chrome Android, the legacy Purpose: prefetch header is used to indicate a link request is a prefetch. See bug 40236973.Edge: Doesn't support Sec-Purpose for <link rel="prefetch">. In Edge, the legacy Purpose: prefetch header is used to indicate a link request is a prefetch. See bug 40236973.Firefox: Sec-Purpose: prefetch replaces the non-standard X-moz: prefetch header that was used to indicate a link prefetch request in earlier versions.Firefox: Prefetch requests should also include the header Accept header string for navigations, but Accept: */* is sent instead.Firefox for Android: Sec-Purpose: prefetch replaces the non-standard X-moz: prefetch header that was used to indicate a link prefetch request in earlier versions.Firefox for Android: Prefetch requests should also include the header Accept header string for navigations, but Accept: */* is sent instead.Quest Browser: Doesn't support Sec-Purpose for <link rel="prefetch">. In Quest Browser, the legacy Purpose: prefetch header is used to indicate a link request is a prefetch. See bug 40236973.Opera: Doesn't support Sec-Purpose for <link rel="prefetch">. In Opera, the legacy Purpose: prefetch header is used to indicate a link request is a prefetch. See bug 40236973.Samsung Internet: Doesn't support Sec-Purpose for <link rel="prefetch">. In Samsung Internet, the legacy Purpose: prefetch header is used to indicate a link request is a prefetch. See bug 40236973.WebView Android: Doesn't support Sec-Purpose for <link rel="prefetch">. In WebView Android, the legacy Purpose: prefetch header is used to indicate a link request is a prefetch. See bug 40236973.
http.headers.Sec-Purpose.speculationrules Chrome2/7/20231315
http.headers.Server-Timing.trailer Firefox12/10/20192470
Firefox: Only the Server-Timing header is a recognized trailer, and it is only exposed to DevTools in the network Timing tab (bug 1403051). Developers cannot access trailers via the Fetch API or XHR.Firefox for Android: Only the Server-Timing header is a recognized trailer, and it is only exposed to DevTools in the network Timing tab (bug 1403051). Developers cannot access trailers via the Fetch API or XHR.
http.headers.Service-Worker-Navigation-Preload 📋Chrome6/5/20173388
http.headers.Set-Cookie.Partitioned 📋Chrome5/30/20231203
http.headers.Set-Cookie.SameSite.Lax_default Firefox9/3/20192568
http.headers.Set-Cookie.SameSite.none_requires_secure Chrome2/4/20202414
http.headers.Set-Cookie.SameSite.schemeful Firefox7/28/20202239
http.headers.Set-Login 📋Chrome12/5/20231014
http.headers.Snapshot-Content-Location Chrome12/6/20173204
http.headers.Speculation-Rules 📋Chrome1/23/2024965
http.headers.Supports-Loading-Mode 📋Chrome1/10/20231343
http.headers.Supports-Loading-Mode.credentialed-prerender Chrome1/10/20231343
http.headers.Supports-Loading-Mode.fenced-frames Chrome9/12/20231098
http.headers.Trailer 📋Firefox12/10/20192470
Firefox: Only the Server-Timing header is a recognized trailer, and it is only exposed to DevTools in the network Timing tab (bug 1403051). Developers cannot access trailers via the Fetch API or XHR.Firefox for Android: Only the Server-Timing header is a recognized trailer, and it is only exposed to DevTools in the network Timing tab (bug 1403051). Developers cannot access trailers via the Fetch API or XHR.
http.headers.Viewport-Width Chrome10/13/20153989
http.headers.WWW-Authenticate.Digest.SHA-256 Firefox10/5/20211805
http.headers.Width Chrome10/13/20153989
http.headers.X-DNS-Prefetch-Control Firefox10/24/20067265
http.mixed-content.allow_file_urls 📋Firefox8/6/20134787
http.mixed-content.allow_localhost_url 📋Chrome12/10/20192470
http.mixed-content.allow_loopback_url 📋Firefox8/8/20173324
http.mixed-content.auto_upgrade_images 📋Chrome10/20/20202155
Firefox: Set security.mixed_content.upgrade_display_content preference to true to allow HTTP fetching and display of upgradable content.Firefox: Set security.mixed_content.block_display_content preference to true to block all mixed content.Firefox for Android: Set security.mixed_content.upgrade_display_content preference to true to allow HTTP fetching and display of upgradable content.Firefox for Android: Set security.mixed_content.block_display_content preference to true to block all mixed content.
http.mixed-content.auto_upgrade_video_audio 📋Chrome2/4/20202414
Firefox: Set security.mixed_content.upgrade_display_content preference to true to allow HTTP fetching and display of upgradable content.Firefox: Set security.mixed_content.block_display_content preference to true to block all mixed content.Firefox for Android: Set security.mixed_content.upgrade_display_content preference to true to allow HTTP fetching and display of upgradable content.Firefox for Android: Set security.mixed_content.block_display_content preference to true to block all mixed content.
http.mixed-content.block_mixed_downloads 📋Firefox7/13/20211889
http.mixed-content.private_network_access 📋Chrome4/16/2024881
http.status.103.preload Chrome6/21/20221546
http.status.425 📋Firefox1/23/20183156