For a given set of browsers what APIs are still considred experimental, and how long have they been experimental?
Below is a list of features that are marked as "Experimental" in Chrome and Firefox
| API | First Browser | Date | Last Browser | Date | Days in experimentation | Notes |
|---|---|---|---|---|---|---|
| html.elements.a.hreftranslate | Chrome | 4/7/2020 | 2270 | |||
| html.elements.a.interestfor | Chrome | 10/28/2025 | 240 | |||
| html.elements.a.target.unfencedTop | Chrome | 6/11/2024 | 744 | |||
| html.elements.area.interestfor | Chrome | 10/28/2025 | 240 | |||
| html.elements.button.interestfor | Chrome | 10/28/2025 | 240 | |||
| html.elements.fencedframe 📋 | Chrome | 6/11/2024 | 744 | |||
| html.elements.fencedframe.allow 📋 | Chrome | 6/11/2024 | 744 | |||
| html.elements.fencedframe.height 📋 | Chrome | 6/11/2024 | 744 | |||
| html.elements.fencedframe.width 📋 | Chrome | 6/11/2024 | 744 | |||
| html.elements.geolocation 📋 | Chrome | 1/13/2026 | 163 | |||
| html.elements.geolocation.autolocate 📋 | Chrome | 1/13/2026 | 163 | |||
| html.elements.geolocation.watch 📋 | Chrome | 1/13/2026 | 163 | |||
| html.elements.iframe.allow.accelerometer 📋 | Chrome | 4/17/2018 | 2991 | |||
| html.elements.iframe.allow.ambient-light-sensor 📋 | Chrome | 4/17/2018 | 2991 | |||
| html.elements.iframe.allow.bluetooth 📋 | Chrome | 8/2/2022 | 1423 | |||
| html.elements.iframe.allow.compute-pressure 📋 | Chrome | 5/14/2024 | 772 | |||
| html.elements.iframe.allow.cross-origin-isolated 📋 | Chrome | 11/17/2020 | 2046 | |||
| html.elements.iframe.allow.document-domain 📋 | Chrome | 1/23/2018 | Firefox | 3/10/2020 | 777 | |
| html.elements.iframe.allow.gamepad 📋 | Firefox | 8/10/2021 | 1780 | Firefox: The default allowlist is * instead of self (as required by the specification).Firefox for Android: The default allowlist is * instead of self (as required by the specification). | ||
| html.elements.iframe.allow.gyroscope 📋 | Chrome | 4/17/2018 | 2991 | |||
| html.elements.iframe.allow.hid 📋 | Chrome | 3/2/2021 | 1941 | |||
| html.elements.iframe.allow.identity-credentials-get 📋 | Chrome | 2/7/2023 | 1234 | |||
| html.elements.iframe.allow.idle-detection 📋 | Chrome | 9/21/2021 | 1738 | |||
| html.elements.iframe.allow.local-fonts 📋 | Chrome | 6/21/2022 | 1465 | |||
| html.elements.iframe.allow.magnetometer 📋 | Chrome | 4/17/2018 | 2991 | |||
| html.elements.iframe.allow.otp-credentials 📋 | Chrome | 8/31/2021 | 1759 | |||
| html.elements.iframe.allow.picture-in-picture 📋 | Chrome | 9/4/2018 | 2851 | |||
| html.elements.iframe.allow.serial 📋 | Chrome | 3/2/2021 | 1941 | |||
| html.elements.iframe.allow.speaker-selection 📋 | Firefox | 8/1/2023 | 1059 | Firefox for Android: Not available due to a limitation in Android (see bug 1473346). | ||
| html.elements.iframe.allow.storage-access 📋 | Chrome | 5/2/2023 | 1150 | |||
| html.elements.iframe.allow.usb 📋 | Chrome | 7/25/2017 | 3257 | |||
| html.elements.iframe.allow.wildcards | Chrome | 11/29/2022 | 1304 | |||
| html.elements.iframe.allow.window-management 📋 | Chrome | 3/29/2022 | 1549 | |||
| html.elements.iframe.allow.xr-spatial-tracking 📋 | Chrome | 12/10/2019 | 2389 | |||
| html.elements.iframe.credentialless 📋 | Chrome | 2/7/2023 | 1234 | |||
| html.elements.iframe.csp 📋 | Chrome | 9/5/2017 | 3215 | |||
| html.elements.iframe.privateToken 📋 | Chrome | 9/12/2023 | 1017 | |||
| html.elements.link.rel.compression-dictionary 📋 | Chrome | 10/15/2024 | 618 | |||
| html.elements.link.rel.expect 📋 | Chrome | 4/16/2024 | 800 | |||
| html.elements.link.rel.modulepreload.as-style 📋 | Chrome | 4/7/2026 | 79 | |||
| html.elements.meta.name.application-title | Chrome | 3/4/2025 | 478 | |||
| html.elements.script.type.speculationrules 📋 | Chrome | 1/10/2023 | 1262 | Chrome: Initial support included same-origin prerendering only.Chrome Android: Initial support included same-origin prerendering only.Edge: Initial support included same-origin prerendering only.Quest Browser: Initial support included same-origin prerendering only.Opera: Initial support included same-origin prerendering only.Opera Android: Initial support included same-origin prerendering only.Samsung Internet: Initial support included same-origin prerendering only.WebView Android: Initial support included same-origin prerendering only. | ||
| html.elements.script.type.speculationrules.eagerness 📋 | Chrome | 1/23/2024 | 884 | Safari: Only conservative is supported for document rules (though moderate automatically falls back to conservative). Only eager and immediate is supported for list rules.Safari on iOS: Only conservative is supported for document rules (though moderate automatically falls back to conservative). Only eager and immediate is supported for list rules. | ||
| html.elements.script.type.speculationrules.expects_no_vary_search 📋 | Chrome | 7/23/2024 | 702 | Chrome: Supported for prefetch only.Chrome Android: Supported for prefetch only.Edge: Supported for prefetch only.Opera: Supported for prefetch only.Opera Android: Supported for prefetch only.Samsung Internet: Supported for prefetch only.WebView Android: Supported for prefetch only. | ||
| html.elements.script.type.speculationrules.prefetch 📋 | Chrome | 2/7/2023 | 1234 | |||
| html.elements.script.type.speculationrules.prerender 📋 | Chrome | 9/2/2022 | 1392 | |||
| html.elements.script.type.speculationrules.referrer_policy 📋 | Chrome | 3/7/2023 | 1206 | |||
| html.elements.script.type.speculationrules.relative_to 📋 | Chrome | 1/23/2024 | 884 | |||
| html.elements.script.type.speculationrules.requires 📋 | Chrome | 2/7/2023 | 1234 | |||
| html.elements.script.type.speculationrules.requires.anonymous-client-ip-when-cross-origin 📋 | Chrome | 2/7/2023 | 1234 | |||
| html.elements.script.type.speculationrules.source_optional 📋 | Chrome | 2/20/2024 | 856 | |||
| html.elements.script.type.speculationrules.tag 📋 | Chrome | 4/29/2025 | 422 | |||
| html.elements.script.type.speculationrules.target_hint 📋 | Chrome | 6/24/2025 | 366 | Chrome: Only "_blank" and "_self" are supported and only for prefetch.Chrome Android: Only "_blank" and "_self" are supported and only for prefetch.Edge: Only "_blank" and "_self" are supported and only for prefetch.Opera: Only "_blank" and "_self" are supported and only for prefetch.Opera Android: Only "_blank" and "_self" are supported and only for prefetch.WebView Android: Only "_blank" and "_self" are supported and only for prefetch. | ||
| html.elements.script.type.speculationrules.urls 📋 | Chrome | 1/10/2023 | 1262 | |||
| html.elements.script.type.speculationrules.where 📋 | Chrome | 1/23/2024 | 884 | |||
| html.elements.selectedcontent 📋 | Chrome | 4/1/2025 | 450 | |||
| html.elements.template.shadowrootreferencetarget | Chrome | 2/4/2025 | Firefox | 3/24/2026 | 413 | |
| html.elements.textarea.autocomplete.webauthn 📋 | Chrome | 11/29/2022 | 1304 | |||
| html.global_attributes.popover.hint 📋 | Chrome | 2/4/2025 | 506 | |||
| html.global_attributes.virtualkeyboardpolicy 📋 | Chrome | 9/21/2021 | 1738 |