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 Safari
| API | First Browser | Date | Last Browser | Date | Days in experimentation | Notes |
|---|---|---|---|---|---|---|
| html.elements.a.attributionsourceid 📋 | Safari | 4/26/2021 | 1885 | |||
| html.elements.a.hreftranslate | Chrome | 4/7/2020 | 2269 | |||
| html.elements.a.interestfor | Chrome | 10/28/2025 | 239 | |||
| html.elements.a.target.unfencedTop | Chrome | 6/11/2024 | 743 | |||
| html.elements.area.interestfor | Chrome | 10/28/2025 | 239 | |||
| html.elements.button.interestfor | Chrome | 10/28/2025 | 239 | |||
| html.elements.fencedframe 📋 | Chrome | 6/11/2024 | 743 | |||
| html.elements.fencedframe.allow 📋 | Chrome | 6/11/2024 | 743 | |||
| html.elements.fencedframe.height 📋 | Chrome | 6/11/2024 | 743 | |||
| html.elements.fencedframe.width 📋 | Chrome | 6/11/2024 | 743 | |||
| html.elements.geolocation 📋 | Chrome | 1/13/2026 | 162 | |||
| html.elements.geolocation.autolocate 📋 | Chrome | 1/13/2026 | 162 | |||
| html.elements.geolocation.watch 📋 | Chrome | 1/13/2026 | 162 | |||
| html.elements.iframe.allow.accelerometer 📋 | Chrome | 4/17/2018 | 2990 | |||
| html.elements.iframe.allow.ambient-light-sensor 📋 | Chrome | 4/17/2018 | 2990 | |||
| html.elements.iframe.allow.bluetooth 📋 | Chrome | 8/2/2022 | 1422 | |||
| html.elements.iframe.allow.compute-pressure 📋 | Chrome | 5/14/2024 | 771 | |||
| html.elements.iframe.allow.cross-origin-isolated 📋 | Chrome | 11/17/2020 | 2045 | |||
| html.elements.iframe.allow.document-domain 📋 | Chrome | 1/23/2018 | 3074 | |||
| html.elements.iframe.allow.gyroscope 📋 | Chrome | 4/17/2018 | 2990 | |||
| html.elements.iframe.allow.hid 📋 | Chrome | 3/2/2021 | 1940 | |||
| html.elements.iframe.allow.identity-credentials-get 📋 | Chrome | 2/7/2023 | 1233 | |||
| html.elements.iframe.allow.idle-detection 📋 | Chrome | 9/21/2021 | 1737 | |||
| html.elements.iframe.allow.local-fonts 📋 | Chrome | 6/21/2022 | 1464 | |||
| html.elements.iframe.allow.magnetometer 📋 | Chrome | 4/17/2018 | 2990 | |||
| html.elements.iframe.allow.otp-credentials 📋 | Chrome | 8/31/2021 | 1758 | |||
| html.elements.iframe.allow.picture-in-picture 📋 | Chrome | 9/4/2018 | 2850 | |||
| html.elements.iframe.allow.serial 📋 | Chrome | 3/2/2021 | 1940 | |||
| html.elements.iframe.allow.storage-access 📋 | Chrome | 5/2/2023 | 1149 | |||
| html.elements.iframe.allow.usb 📋 | Chrome | 7/25/2017 | 3256 | |||
| html.elements.iframe.allow.wildcards | Chrome | 11/29/2022 | 1303 | |||
| html.elements.iframe.allow.window-management 📋 | Chrome | 3/29/2022 | 1548 | |||
| html.elements.iframe.allow.xr-spatial-tracking 📋 | Chrome | 12/10/2019 | 2388 | |||
| html.elements.iframe.credentialless 📋 | Chrome | 2/7/2023 | 1233 | |||
| html.elements.iframe.csp 📋 | Chrome | 9/5/2017 | 3214 | |||
| html.elements.iframe.privateToken 📋 | Chrome | 9/12/2023 | 1016 | |||
| html.elements.input.alpha 📋 | Safari | 3/31/2025 | 450 | |||
| html.elements.input.colorspace 📋 | Safari | 3/31/2025 | 450 | |||
| html.elements.input.switch | Safari | 3/5/2024 | 841 | |||
| html.elements.link.rel.compression-dictionary 📋 | Chrome | 10/15/2024 | 617 | |||
| html.elements.link.rel.expect 📋 | Chrome | 4/16/2024 | 799 | |||
| html.elements.link.rel.modulepreload.as-style 📋 | Chrome | 4/7/2026 | 78 | |||
| html.elements.meta.name.application-title | Chrome | 3/4/2025 | 477 | |||
| html.elements.script.type.speculationrules 📋 | Chrome | 1/10/2023 | Safari | 12/12/2025 | 1067 | 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 | Safari | 12/12/2025 | 689 | 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 | 701 | 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 | Safari | 12/12/2025 | 1039 | |
| html.elements.script.type.speculationrules.prerender 📋 | Chrome | 9/2/2022 | 1391 | |||
| html.elements.script.type.speculationrules.referrer_policy 📋 | Chrome | 3/7/2023 | Safari | 12/12/2025 | 1011 | |
| html.elements.script.type.speculationrules.relative_to 📋 | Chrome | 1/23/2024 | Safari | 12/12/2025 | 689 | |
| html.elements.script.type.speculationrules.requires 📋 | Chrome | 2/7/2023 | 1233 | |||
| html.elements.script.type.speculationrules.requires.anonymous-client-ip-when-cross-origin 📋 | Chrome | 2/7/2023 | 1233 | |||
| html.elements.script.type.speculationrules.source_optional 📋 | Chrome | 2/20/2024 | Safari | 12/12/2025 | 661 | |
| html.elements.script.type.speculationrules.tag 📋 | Chrome | 4/29/2025 | Safari | 12/12/2025 | 227 | |
| html.elements.script.type.speculationrules.target_hint 📋 | Chrome | 6/24/2025 | 365 | 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 | Safari | 12/12/2025 | 1067 | |
| html.elements.script.type.speculationrules.where 📋 | Chrome | 1/23/2024 | Safari | 12/12/2025 | 689 | |
| html.elements.selectedcontent 📋 | Chrome | 4/1/2025 | 449 | |||
| html.elements.template.shadowrootreferencetarget | Chrome | 2/4/2025 | Safari | 9/15/2025 | 223 | |
| html.elements.textarea.autocomplete.webauthn 📋 | Chrome | 11/29/2022 | 1303 | |||
| html.global_attributes.popover.hint 📋 | Chrome | 2/4/2025 | 505 | |||
| html.global_attributes.virtualkeyboardpolicy 📋 | Chrome | 9/21/2021 | 1737 |