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 Safari
In Chrome 196
In Safari 4

Unstable APIs

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

Raw Data

Quick Links:

HTTP Data

API First Browser Date Days in Limbo Notes
http.headers.Accept-CH 📋Chrome10/13/20153810
http.headers.Accept-CH.Content-DPR Chrome10/13/20153810
http.headers.Accept-CH.DPR Chrome10/13/20153810
http.headers.Accept-CH.Device-Memory Chrome9/5/20173117
http.headers.Accept-CH.Sec-CH-DPR 📋Chrome1/4/20221535
http.headers.Accept-CH.Sec-CH-Device-Memory 📋Chrome1/4/20221535
http.headers.Accept-CH.Sec-CH-UA Chrome3/2/20211843
http.headers.Accept-CH.Sec-CH-UA-Arch Chrome3/2/20211843
http.headers.Accept-CH.Sec-CH-UA-Full-Version Chrome3/2/20211843
http.headers.Accept-CH.Sec-CH-UA-Mobile Chrome3/2/20211843
http.headers.Accept-CH.Sec-CH-UA-Model Chrome3/2/20211843
http.headers.Accept-CH.Sec-CH-UA-Platform Chrome3/2/20211843
http.headers.Accept-CH.Sec-CH-UA-Platform-Version Chrome3/2/20211843
http.headers.Accept-CH.Sec-CH-Viewport-Height 📋Chrome9/2/20221294
http.headers.Accept-CH.Sec-CH-Viewport-Width 📋Chrome1/4/20221535
http.headers.Accept-CH.Sec-CH-Width 📋Chrome1/4/20221535
http.headers.Accept-CH.Viewport-Width Chrome10/13/20153810
http.headers.Accept-CH.Width Chrome10/13/20153810
http.headers.Accept-Encoding.dcb Chrome10/15/2024520
http.headers.Accept-Encoding.dcz Chrome10/15/2024520
http.headers.Activate-Storage-Access 📋Chrome2/4/2025408
http.headers.Attribution-Reporting-Eligible 📋Chrome9/12/2023919
http.headers.Attribution-Reporting-Register-Source 📋Chrome9/12/2023919
http.headers.Attribution-Reporting-Register-Trigger 📋Chrome9/12/2023919
http.headers.Attribution-Reporting-Support 📋Chrome9/12/2023919
http.headers.Authorization.Digest.SHA-256 Chrome9/12/2023919
http.headers.Authorization.authorization_removed_cross_origin 📋Safari10/24/20221242
http.headers.Available-Dictionary 📋Chrome10/15/2024520
http.headers.Cache-Control.immutable Safari9/19/20173103
http.headers.Clear-Site-Data.clientHints 📋Chrome9/12/2023919
http.headers.Clear-Site-Data.prefetchCache Chrome6/24/2025268
http.headers.Clear-Site-Data.prerenderCache Chrome6/24/2025268
http.headers.Content-DPR Chrome10/13/20153810
http.headers.Content-Encoding.dcb Chrome10/15/2024520
http.headers.Content-Encoding.dcz Chrome10/15/2024520
http.headers.Content-Security-Policy.fenced-frame-src 📋Chrome6/11/2024646
http.headers.Content-Security-Policy.prefetch-src Safari1/23/20231151
http.headers.Content-Security-Policy.script-src.trusted-types-eval 📋Safari9/15/2025185
http.headers.Critical-CH 📋Chrome5/25/20211759
http.headers.Cross-Origin-Embedder-Policy.credentialless 📋Chrome11/15/20211585
http.headers.Cross-Origin-Embedder-Policy.report-to_parameter 📋Chrome11/15/20211585
http.headers.Cross-Origin-Opener-Policy.report-to_parameter 📋Chrome11/15/20211585
http.headers.DNT Chrome11/6/20124881
http.headers.DPR Chrome10/13/20153810
http.headers.Device-Memory Chrome9/5/20173117
Chrome: From Chrome 147, reported values are 2, 4, 8, 16, and 32.Chrome: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Chrome Android: From Chrome 147, reported values are 1, 2, 4, and 8.Chrome Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Edge: From Edge 147, reported values are 2, 4, 8, 16, and 32.Edge: Before Edge 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Quest Browser: From Chrome 147, reported values are 1, 2, 4, and 8.Quest Browser: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Opera: From Opera false, reported values are 2, 4, 8, 16, and 32.Opera: Before Opera false, reported values were 0.25, 0.5, 1, 2, 4, and 8.Opera Android: From Chrome 147, reported values are 1, 2, 4, and 8.Opera Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Samsung Internet: From Chrome 147, reported values are 1, 2, 4, and 8.Samsung Internet: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.WebView Android: From Chrome 147, reported values are 1, 2, 4, and 8.WebView Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.
http.headers.Dictionary-ID 📋Chrome10/15/2024520
http.headers.Downlink 📋Chrome5/29/20182851
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 📋Chrome5/29/20182851
http.headers.Feature-Policy Chrome7/25/20173159
http.headers.Feature-Policy.accelerometer 📋Chrome4/17/20182893
http.headers.Feature-Policy.ambient-light-sensor 📋Chrome4/17/20182893
http.headers.Feature-Policy.attribution-reporting 📋Chrome9/12/2023919
http.headers.Feature-Policy.autoplay 📋Chrome1/23/20182977
http.headers.Feature-Policy.bluetooth 📋Chrome8/2/20221325
http.headers.Feature-Policy.browsing-topics Chrome7/18/2023975
http.headers.Feature-Policy.camera 📋Chrome1/23/20182977
http.headers.Feature-Policy.compute-pressure 📋Chrome5/14/2024674
http.headers.Feature-Policy.cross-origin-isolated 📋Chrome11/17/20201948
http.headers.Feature-Policy.deferred-fetch 📋Chrome4/1/2025352
http.headers.Feature-Policy.deferred-fetch-minimal 📋Chrome4/1/2025352
http.headers.Feature-Policy.display-capture 📋Chrome9/21/20211640
http.headers.Feature-Policy.document-domain 📋Chrome1/23/20182977
http.headers.Feature-Policy.encrypted-media 📋Chrome1/23/20182977
http.headers.Feature-Policy.fullscreen 📋Chrome10/17/20173075
http.headers.Feature-Policy.geolocation 📋Chrome1/23/20182977
http.headers.Feature-Policy.gyroscope 📋Chrome4/17/20182893
http.headers.Feature-Policy.hid 📋Chrome3/2/20211843
http.headers.Feature-Policy.identity-credentials-get 📋Chrome2/7/20231136
http.headers.Feature-Policy.idle-detection 📋Chrome9/21/20211640
http.headers.Feature-Policy.local-fonts 📋Chrome6/21/20221367
http.headers.Feature-Policy.magnetometer 📋Chrome4/17/20182893
http.headers.Feature-Policy.microphone 📋Chrome1/23/20182977
http.headers.Feature-Policy.midi 📋Chrome1/23/20182977
http.headers.Feature-Policy.otp-credentials 📋Chrome8/31/20211661
http.headers.Feature-Policy.payment 📋Chrome7/25/20173159
http.headers.Feature-Policy.picture-in-picture 📋Chrome9/4/20182753
http.headers.Feature-Policy.publickey-credentials-create 📋Chrome7/27/20202061
http.headers.Feature-Policy.publickey-credentials-get 📋Chrome7/27/20202061
http.headers.Feature-Policy.screen-wake-lock 📋Chrome7/27/20202061
http.headers.Feature-Policy.serial 📋Chrome3/2/20211843
http.headers.Feature-Policy.storage-access 📋Chrome5/2/20231052
http.headers.Feature-Policy.usb 📋Chrome7/25/20173159
http.headers.Feature-Policy.web-share 📋Chrome10/20/20201976
http.headers.Feature-Policy.wildcards Chrome11/29/20221206
http.headers.Feature-Policy.window-management 📋Chrome3/29/20221451
http.headers.Feature-Policy.xr-spatial-tracking 📋Chrome12/10/20192291
http.headers.Integrity-Policy 📋Chrome6/24/2025268
Firefox: Reporting endpoints are ignored (violations are logged to console).Firefox for Android: Reporting endpoints are ignored (violations are logged to console).
http.headers.Integrity-Policy.blocked-destinations_script 📋Chrome6/24/2025268
http.headers.Integrity-Policy-Report-Only 📋Chrome6/24/2025268
Firefox: Reporting endpoints are ignored (violations are logged to console).Firefox for Android: Reporting endpoints are ignored (violations are logged to console).
http.headers.Integrity-Policy-Report-Only.blocked-destinations_script 📋Chrome6/24/2025268
http.headers.NEL 📋Chrome12/4/20182662
http.headers.No-Vary-Search 📋Chrome9/30/2025170
Chrome: Before Chrome 127, speculation rules are only supported for navigational prefetch, not prerender.Chrome: Before Chrome 141, HTTP cache is not supported.Chrome Android: Before Chrome Android 127, speculation rules are only supported for navigational prefetch, not prerender.Chrome Android: Before Chrome Android 141, HTTP cache is not supported.Edge: Before Edge 127, speculation rules are only supported for navigational prefetch, not prerender.Edge: Before Edge 141, HTTP cache is not supported.Opera: Before Opera 113, speculation rules are only supported for navigational prefetch, not prerender.Opera: Before Opera 125, HTTP cache is not supported.Opera Android: Before Opera Android 84, speculation rules are only supported for navigational prefetch, not prerender.Opera Android: Before Opera Android 93, HTTP cache is not supported.Samsung Internet: Before Samsung Internet 28.0, speculation rules are only supported for navigational prefetch, not prerender.Samsung Internet: Before Samsung Internet false, HTTP cache is not supported.WebView Android: Before WebView Android 127, speculation rules are only supported for navigational prefetch, not prerender.WebView Android: Before WebView Android 141, HTTP cache is not supported.
http.headers.No-Vary-Search.http_cache 📋Chrome9/30/2025170
http.headers.No-Vary-Search.speculation_rules_prefetch 📋Chrome1/23/2024786
http.headers.No-Vary-Search.speculation_rules_prerender 📋Chrome7/23/2024604
http.headers.Observe-Browsing-Topics Chrome7/18/2023975
http.headers.Origin-Agent-Cluster 📋Chrome4/13/20211801
http.headers.Permissions-Policy 📋Chrome1/19/20211885
http.headers.Permissions-Policy.accelerometer 📋Chrome1/19/20211885
http.headers.Permissions-Policy.ambient-light-sensor 📋Chrome4/17/20182893
http.headers.Permissions-Policy.aria-notify Chrome9/30/2025170
Chrome: Not supported on ChromeOS.Chrome Android: Not supported on ChromeOS.Edge: Not supported on ChromeOS.Opera: Not supported on ChromeOS.Opera Android: Not supported on ChromeOS.WebView Android: Not supported on ChromeOS.
http.headers.Permissions-Policy.attribution-reporting 📋Chrome9/12/2023919
http.headers.Permissions-Policy.autoplay 📋Chrome1/19/20211885
http.headers.Permissions-Policy.bluetooth 📋Chrome8/2/20221325
http.headers.Permissions-Policy.browsing-topics Chrome7/18/2023975
http.headers.Permissions-Policy.camera 📋Chrome1/19/20211885
http.headers.Permissions-Policy.captured-surface-control 📋Chrome4/29/2025324
http.headers.Permissions-Policy.ch-ua-high-entropy-values 📋Chrome1/13/202665
http.headers.Permissions-Policy.compute-pressure 📋Chrome5/14/2024674
http.headers.Permissions-Policy.cross-origin-isolated 📋Chrome1/19/20211885
http.headers.Permissions-Policy.deferred-fetch 📋Chrome4/1/2025352
http.headers.Permissions-Policy.deferred-fetch-minimal 📋Chrome4/1/2025352
http.headers.Permissions-Policy.display-capture 📋Chrome9/21/20211640
http.headers.Permissions-Policy.encrypted-media 📋Chrome1/19/20211885
http.headers.Permissions-Policy.fullscreen 📋Chrome1/19/20211885
http.headers.Permissions-Policy.gamepad 📋Chrome6/21/20221367
http.headers.Permissions-Policy.geolocation 📋Chrome1/19/20211885
http.headers.Permissions-Policy.gyroscope 📋Chrome1/19/20211885
http.headers.Permissions-Policy.hid 📋Chrome3/2/20211843
http.headers.Permissions-Policy.identity-credentials-get 📋Chrome2/7/20231136
http.headers.Permissions-Policy.idle-detection 📋Chrome9/21/20211640
http.headers.Permissions-Policy.local-fonts 📋Chrome6/21/20221367
http.headers.Permissions-Policy.magnetometer 📋Chrome4/17/20182893
http.headers.Permissions-Policy.microphone 📋Chrome1/19/20211885
http.headers.Permissions-Policy.midi 📋Chrome1/19/20211885
http.headers.Permissions-Policy.on-device-speech-recognition 📋Chrome10/28/2025142
http.headers.Permissions-Policy.otp-credentials 📋Chrome8/31/20211661
http.headers.Permissions-Policy.payment 📋Chrome1/19/20211885
http.headers.Permissions-Policy.picture-in-picture 📋Chrome1/19/20211885
http.headers.Permissions-Policy.private-state-token-issuance 📋Chrome9/12/2023919
http.headers.Permissions-Policy.private-state-token-redemption 📋Chrome9/12/2023919
http.headers.Permissions-Policy.publickey-credentials-create 📋Chrome1/19/20211885
http.headers.Permissions-Policy.publickey-credentials-get 📋Chrome1/19/20211885
http.headers.Permissions-Policy.screen-wake-lock 📋Chrome1/19/20211885
http.headers.Permissions-Policy.serial 📋Chrome3/2/20211843
http.headers.Permissions-Policy.storage-access 📋Chrome5/2/20231052
http.headers.Permissions-Policy.summarizer 📋Chrome6/24/2025268
http.headers.Permissions-Policy.usb 📋Chrome1/19/20211885
http.headers.Permissions-Policy.web-share 📋Chrome1/19/20211885
http.headers.Permissions-Policy.wildcards Chrome11/29/20221206
http.headers.Permissions-Policy.window-management 📋Chrome3/29/20221451
http.headers.Permissions-Policy.xr-spatial-tracking 📋Chrome1/19/20211885
http.headers.Priority 📋Chrome4/16/2024702
http.headers.RTT 📋Chrome5/29/20182851
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 Chrome1/25/20173340
http.headers.Referrer-Policy.origin-when-cross-origin Chrome1/25/20173340
http.headers.Referrer-Policy.unsafe-url Chrome1/25/20173340
http.headers.Report-To Chrome10/16/20182711
http.headers.Retry-After 📋Chrome1/10/20134816
http.headers.Save-Data 📋Chrome3/2/20163669
http.headers.Sec-Browsing-Topics Chrome7/18/2023975
http.headers.Sec-CH-DPR 📋Chrome1/4/20221535
http.headers.Sec-CH-Device-Memory 📋Chrome1/4/20221535
Chrome: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Chrome: From Chrome 147, reported values are 2, 4, 8, 16, and 32.Chrome: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Chrome: From Chrome 147, reported values are 2, 4, 8, 16, and 32.Chrome Android: From Chrome 147, reported values are 1, 2, 4, and 8.Chrome Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Chrome Android: From Chrome 147, reported values are 1, 2, 4, and 8.Chrome Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Edge: Before Edge 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Edge: From Edge 147, reported values are 2, 4, 8, 16, and 32.Edge: Before Edge 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Edge: From Edge 147, reported values are 2, 4, 8, 16, and 32.Quest Browser: From Chrome 147, reported values are 1, 2, 4, and 8.Quest Browser: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Quest Browser: From Chrome 147, reported values are 1, 2, 4, and 8.Quest Browser: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Opera: Before Opera false, reported values were 0.25, 0.5, 1, 2, 4, and 8.Opera: From Opera false, reported values are 2, 4, 8, 16, and 32.Opera: Before Opera false, reported values were 0.25, 0.5, 1, 2, 4, and 8.Opera: From Opera false, reported values are 2, 4, 8, 16, and 32.Opera Android: From Chrome 147, reported values are 1, 2, 4, and 8.Opera Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Opera Android: From Chrome 147, reported values are 1, 2, 4, and 8.Opera Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Samsung Internet: From Chrome 147, reported values are 1, 2, 4, and 8.Samsung Internet: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.Samsung Internet: From Chrome 147, reported values are 1, 2, 4, and 8.Samsung Internet: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.WebView Android: From Chrome 147, reported values are 1, 2, 4, and 8.WebView Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.WebView Android: From Chrome 147, reported values are 1, 2, 4, and 8.WebView Android: Before Chrome 147, reported values were 0.25, 0.5, 1, 2, 4, and 8.
http.headers.Sec-CH-Prefers-Color-Scheme 📋Chrome8/31/20211661
http.headers.Sec-CH-Prefers-Reduced-Motion 📋Chrome11/29/20221206
http.headers.Sec-CH-Prefers-Reduced-Transparency 📋Chrome10/31/2023870
http.headers.Sec-CH-UA 📋Chrome3/2/20211843
http.headers.Sec-CH-UA-Arch 📋Chrome3/2/20211843
http.headers.Sec-CH-UA-Bitness 📋Chrome8/31/20211661
http.headers.Sec-CH-UA-Form-Factors 📋Chrome4/16/2024702
http.headers.Sec-CH-UA-Full-Version 📋Chrome3/2/20211843
http.headers.Sec-CH-UA-Full-Version-List 📋Chrome2/1/20221507
http.headers.Sec-CH-UA-Mobile 📋Chrome3/2/20211843
http.headers.Sec-CH-UA-Model 📋Chrome3/2/20211843
http.headers.Sec-CH-UA-Platform 📋Chrome3/2/20211843
http.headers.Sec-CH-UA-Platform-Version 📋Chrome3/2/20211843
http.headers.Sec-CH-UA-WoW64 📋Chrome3/29/20221451
http.headers.Sec-CH-Viewport-Height 📋Chrome9/2/20221294
http.headers.Sec-CH-Viewport-Width 📋Chrome1/4/20221535
http.headers.Sec-CH-Width 📋Chrome1/4/20221535
http.headers.Sec-Fetch-Dest.fencedframe Chrome6/11/2024646
http.headers.Sec-Fetch-Storage-Access 📋Chrome2/4/2025408
http.headers.Sec-Fetch-User 📋Chrome7/30/20192424
http.headers.Sec-Private-State-Token 📋Chrome9/12/2023919
http.headers.Sec-Private-State-Token-Crypto-Version 📋Chrome9/12/2023919
http.headers.Sec-Private-State-Token-Lifetime 📋Chrome9/12/2023919
http.headers.Sec-Purpose 📋Chrome2/7/20231136
http.headers.Sec-Redemption-Record 📋Chrome9/12/2023919
http.headers.Set-Cookie.SameSite.Lax_default Chrome2/4/20202235
http.headers.Set-Cookie.SameSite.none_requires_secure Chrome2/4/20202235
http.headers.Set-Cookie.SameSite.schemeful Chrome5/25/20211759
http.headers.Set-Cookie.http_host-http_prefixes Chrome9/2/2025198
Firefox: __Host-Http- is supported under its original name __HostHttp-. See bug 1982555.Firefox for Android: __Host-Http- is supported under its original name __HostHttp-. See bug 1982555.
http.headers.Set-Login 📋Chrome12/5/2023835
http.headers.Snapshot-Content-Location Chrome12/6/20173025
http.headers.Supports-Loading-Mode 📋Chrome1/10/20231164
http.headers.Supports-Loading-Mode.credentialed-prerender 📋Chrome1/10/20231164
http.headers.Supports-Loading-Mode.fenced-frame 📋Chrome9/12/2023919
http.headers.Use-As-Dictionary 📋Chrome10/15/2024520
http.headers.Viewport-Width Chrome10/13/20153810
http.headers.WWW-Authenticate.Digest.SHA-256 Chrome9/12/2023919
http.headers.Width Chrome10/13/20153810
http.headers.X-DNS-Prefetch-Control Chrome12/11/20086307
http.mixed-content.allow_file_urls 📋Chrome12/10/20192291
http.mixed-content.allow_localhost_url 📋Chrome12/10/20192291
http.mixed-content.allow_loopback_url 📋Chrome12/10/20192291
http.mixed-content.auto_upgrade_images 📋Chrome10/20/20201976
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 📋Chrome2/4/20202235
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 📋Chrome7/20/20211703
http.mixed-content.private_network_access 📋Chrome6/24/2025268
http.status.103.preload Chrome6/21/20221367