Experimental

For a given set of browsers what APIs are still considred experimental, and how long have they been experimental?

Example Comparisons
Browsers
Features

Summary

Experimental APIs

Below is a list of features that are marked as "Experimental" in Chrome and Firefox

Raw Data

Quick Links:

HTTP Data

API First Browser Date Last Browser Date Days in experimentation Notes
http.headers.Accept-CH.Sec-CH-DPR 📋Chrome1/4/2022 1535
http.headers.Accept-CH.Sec-CH-Device-Memory 📋Chrome1/4/2022 1535
http.headers.Accept-CH.Sec-CH-UA Chrome3/2/2021 1843
http.headers.Accept-CH.Sec-CH-UA-Arch Chrome3/2/2021 1843
http.headers.Accept-CH.Sec-CH-UA-Full-Version Chrome3/2/2021 1843
http.headers.Accept-CH.Sec-CH-UA-Mobile Chrome3/2/2021 1843
http.headers.Accept-CH.Sec-CH-UA-Model Chrome3/2/2021 1843
http.headers.Accept-CH.Sec-CH-UA-Platform Chrome3/2/2021 1843
http.headers.Accept-CH.Sec-CH-UA-Platform-Version Chrome3/2/2021 1843
http.headers.Accept-CH.Sec-CH-Viewport-Height 📋Chrome9/2/2022 1294
http.headers.Accept-CH.Sec-CH-Viewport-Width 📋Chrome1/4/2022 1535
http.headers.Accept-CH.Sec-CH-Width 📋Chrome1/4/2022 1535
http.headers.Accept-Encoding.dcb Chrome10/15/2024 520
http.headers.Accept-Encoding.dcz Chrome10/15/2024 520
http.headers.Available-Dictionary 📋Chrome10/15/2024 520
http.headers.Clear-Site-Data.clientHints 📋Chrome9/12/2023 919
http.headers.Clear-Site-Data.prefetchCache Chrome6/24/2025 268
http.headers.Clear-Site-Data.prerenderCache Chrome6/24/2025 268
http.headers.Content-Encoding.dcb Chrome10/15/2024 520
http.headers.Content-Encoding.dcz Chrome10/15/2024 520
http.headers.Content-Security-Policy.fenced-frame-src 📋Chrome6/11/2024 646
http.headers.Content-Security-Policy.script-src.inline-speculation-rules Chrome2/7/2023 1136
http.headers.Critical-CH 📋Chrome5/25/2021 1759
http.headers.Dictionary-ID 📋Chrome10/15/2024 520
http.headers.Downlink 📋Chrome5/29/2018 2851
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 📋Chrome5/29/2018 2851
http.headers.Early-Data 📋Firefox1/23/2018 2977
http.headers.Idempotency-Key 📋Firefox2/4/2025 408
Firefox: Automatically adds a unique 64-bit key for POST requests when needed, if not set in JavaScript.
http.headers.Integrity-Policy.blocked-destinations_style 📋Firefox8/19/2025 212
http.headers.Integrity-Policy-Report-Only.blocked-destinations_style 📋Firefox8/19/2025 212
http.headers.NEL 📋Chrome12/4/2018 2662
http.headers.No-Vary-Search 📋Chrome9/30/2025 170
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 📋Chrome9/30/2025 170
http.headers.No-Vary-Search.speculation_rules_prefetch 📋Chrome1/23/2024 786
http.headers.No-Vary-Search.speculation_rules_prerender 📋Chrome7/23/2024 604
http.headers.Permissions-Policy 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.accelerometer 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.ambient-light-sensor 📋Chrome4/17/2018 2893
http.headers.Permissions-Policy.aria-notify Chrome9/30/2025 170
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.autoplay 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.bluetooth 📋Chrome8/2/2022 1325
http.headers.Permissions-Policy.camera 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.captured-surface-control 📋Chrome4/29/2025 324
http.headers.Permissions-Policy.ch-ua-high-entropy-values 📋Chrome1/13/2026 65
http.headers.Permissions-Policy.compute-pressure 📋Chrome5/14/2024 674
http.headers.Permissions-Policy.cross-origin-isolated 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.deferred-fetch 📋Chrome4/1/2025 352
http.headers.Permissions-Policy.deferred-fetch-minimal 📋Chrome4/1/2025 352
http.headers.Permissions-Policy.display-capture 📋Chrome9/21/2021 1640
http.headers.Permissions-Policy.encrypted-media 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.fullscreen 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.gamepad 📋Chrome6/21/2022 1367
http.headers.Permissions-Policy.geolocation 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.gyroscope 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.hid 📋Chrome3/2/2021 1843
http.headers.Permissions-Policy.identity-credentials-get 📋Chrome2/7/2023 1136
http.headers.Permissions-Policy.idle-detection 📋Chrome9/21/2021 1640
http.headers.Permissions-Policy.local-fonts 📋Chrome6/21/2022 1367
http.headers.Permissions-Policy.magnetometer 📋Chrome4/17/2018 2893
http.headers.Permissions-Policy.microphone 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.midi 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.on-device-speech-recognition 📋Chrome10/28/2025 142
http.headers.Permissions-Policy.otp-credentials 📋Chrome8/31/2021 1661
http.headers.Permissions-Policy.payment 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.picture-in-picture 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.private-state-token-issuance 📋Chrome9/12/2023 919
http.headers.Permissions-Policy.private-state-token-redemption 📋Chrome9/12/2023 919
http.headers.Permissions-Policy.publickey-credentials-create 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.publickey-credentials-get 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.screen-wake-lock 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.serial 📋Chrome3/2/2021 1843
http.headers.Permissions-Policy.storage-access 📋Chrome5/2/2023 1052
http.headers.Permissions-Policy.summarizer 📋Chrome6/24/2025 268
http.headers.Permissions-Policy.usb 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.web-share 📋Chrome1/19/2021 1885
http.headers.Permissions-Policy.wildcards Chrome11/29/2022 1206
http.headers.Permissions-Policy.window-management 📋Chrome3/29/2022 1451
http.headers.Permissions-Policy.xr-spatial-tracking 📋Chrome1/19/2021 1885
http.headers.RTT 📋Chrome5/29/2018 2851
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.Save-Data 📋Chrome3/2/2016 3669
http.headers.Sec-CH-DPR 📋Chrome1/4/2022 1535
http.headers.Sec-CH-Device-Memory 📋Chrome1/4/2022 1535
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 📋Chrome8/31/2021 1661
http.headers.Sec-CH-Prefers-Reduced-Motion 📋Chrome11/29/2022 1206
http.headers.Sec-CH-Prefers-Reduced-Transparency 📋Chrome10/31/2023 870
http.headers.Sec-CH-UA 📋Chrome3/2/2021 1843
http.headers.Sec-CH-UA-Arch 📋Chrome3/2/2021 1843
http.headers.Sec-CH-UA-Bitness 📋Chrome8/31/2021 1661
http.headers.Sec-CH-UA-Form-Factors 📋Chrome4/16/2024 702
http.headers.Sec-CH-UA-Full-Version-List 📋Chrome2/1/2022 1507
http.headers.Sec-CH-UA-Mobile 📋Chrome3/2/2021 1843
http.headers.Sec-CH-UA-Model 📋Chrome3/2/2021 1843
http.headers.Sec-CH-UA-Platform 📋Chrome3/2/2021 1843
http.headers.Sec-CH-UA-Platform-Version 📋Chrome3/2/2021 1843
http.headers.Sec-CH-UA-WoW64 📋Chrome3/29/2022 1451
http.headers.Sec-CH-Viewport-Height 📋Chrome9/2/2022 1294
http.headers.Sec-CH-Viewport-Width 📋Chrome1/4/2022 1535
http.headers.Sec-CH-Width 📋Chrome1/4/2022 1535
http.headers.Sec-Fetch-Dest.fencedframe Chrome6/11/2024 646
http.headers.Sec-GPC 📋Firefox11/21/2023 849
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.Firefox for Android: Opt-in to GPC using the Enhanced Tracking Protection toggle 'Tell web sites not to share & sell data', or by setting the preference privacy.globalprivacycontrol.enabled to true.
http.headers.Sec-Private-State-Token 📋Chrome9/12/2023 919
http.headers.Sec-Private-State-Token-Crypto-Version 📋Chrome9/12/2023 919
http.headers.Sec-Private-State-Token-Lifetime 📋Chrome9/12/2023 919
http.headers.Sec-Purpose.speculationrules Chrome2/7/2023 1136
http.headers.Sec-Redemption-Record 📋Chrome9/12/2023 919
http.headers.Sec-Speculation-Tags 📋Chrome4/29/2025 324
http.headers.Speculation-Rules 📋Chrome1/23/2024 786
http.headers.Supports-Loading-Mode 📋Chrome1/10/2023 1164
http.headers.Supports-Loading-Mode.credentialed-prerender 📋Chrome1/10/2023 1164
http.headers.Supports-Loading-Mode.fenced-frame 📋Chrome9/12/2023 919
http.headers.Use-As-Dictionary 📋Chrome10/15/2024 520