Time to Stable

For a given set of browsers, what APIs are in all of them and how many days it take for the API to land in the first browser to the last.

Example Comparisons
Browsers
Features

Summary

A count of the number of APIs that landed in A first and B last.
Last in FirefoxLast in Safari
First in Firefox 78
First in Safari 91

Average time for an API to become available across Firefox and Safari

169 APIs took an average of 619.30 days to become available to use.

API breakdown:

Average time to landing by year of first landing

If a feature landed in the earliest browser in 20XX it took Y days on average to become available in the last browser (when considering Firefox and Safari). TTA (time to available).
HTTP APIsHTTP TTA
2003 58599.14
2004 43269.00
2006 4511.00
2008 1720.00
2009 10148.00
2010 1435.00
2011 1945.00
2012 6188.67
2013 17426.88
2015 61075.67
2016 12481.08
2017 4759.00
2018 141158.43
2019 6257.00
2020 2503.00
2021 4511.75
2022 9352.33
2023 7308.00
2024 2638.00
2025 1143.00

The Tortoise and the Hare

There is a natural tension on the web with respect to browser engines. Every engine has their own set of priorities which define the level of investment that they choose to make and on which areas they choose to make it.

A developer naturally wants their experiences to be available to the widest audience possible and these differing priorities create an unevenness on the platform (a lumpiness) making it harder for developers to build experiences that work everywhere.

This section highlights where browsers are pushing and pulling on the platform.

Sprinters

This table is designed to show which browsers are pushing on the platform the most.

Adding features to quickly is not always desired because developers are unlikely to adopt those features in their sites or apps.

For a given year, if a feature landed in Browser X first, how many days it take on average to be available in Firefox and Safari. TTA (time to available).
Year HTTPHTTP TTA
2003
  Safari 58599.14
2004
  Firefox 43269.00
2006
  Firefox 4511.00
2008
  Firefox 1720.00
2009
  Safari 10148.00
2010
  Safari 1435.00
2011
  Firefox 1945.00
2012
  Firefox 6188.67
2013
  Firefox 13212.54
  Safari 41123.50
2015
  Firefox 61075.67
2016
  Firefox 10522.70
  Safari 2273.00
2017
  Firefox 4759.00
2018
  Firefox 131206.00
  Safari 1540.00
2019
  Firefox 5162.60
  Safari 1729.00
2020
  Firefox 2503.00
2021
  Firefox 4511.75
2022
  Safari 7285.71
  Firefox 2585.50
2023
  Safari 7308.00
2024
  Firefox 2638.00
2025
  Firefox 1143.00

Plodders

This table is designed to show which browsers are pulling on the platform the most.

For a feature that first landed in year X, how many days did it take on average for the last browser to catch up across Firefox and Safari. TTA (time to available).
Year HTTP countHTTP TTA
2003
  Firefox 58599.14
2004
  Safari 43269.00
2006
  Safari 4511.00
2008
  Safari 1720.00
2009
  Firefox 10148.00
2010
  Firefox 1435.00
2011
  Safari 1945.00
2012
  Safari 6188.67
2013
  Safari 13212.54
  Firefox 41123.50
2015
  Safari 61075.67
2016
  Safari 10522.70
  Firefox 2273.00
2017
  Safari 4759.00
2018
  Safari 131206.00
  Firefox 1540.00
2019
  Safari 5162.60
  Firefox 1729.00
2020
  Safari 2503.00
2021
  Safari 4511.75
2022
  Firefox 7285.71
  Safari 2585.50
2023
  Firefox 7308.00
2024
  Safari 2638.00
2025
  Safari 1143.00

Stable APIs

Below is a list of features that are in Firefox and Safari

Raw Data

Quick Links:

HTTP Data

API First Browser Date Last Browser Date Days Notes
http.data-url 📋Firefox10/24/2006 Safari3/18/2008511
Edge: Before Edge 79, the maximum size supported is 4GB.Internet Explorer: Since Internet Explorer 9, the maximum size supported is 4GB.Internet Explorer: In Internet Explorer 8, the maximum size supported is 32kB.
http.data-url.css_files Firefox10/24/2006 Safari3/18/2008511
http.data-url.html_files Firefox10/24/2006 Safari3/18/2008511
http.data-url.js_files Firefox10/24/2006 Safari3/18/2008511
http.data-url.top_level_navigation_blocked Firefox3/13/2018 Safari9/16/2020918
http.headers.Accept 📋Safari6/23/2003 Firefox11/9/2004505
Firefox: In Firefox 66, the default Accept header value changed to */*.Firefox for Android: In Firefox for Android 66, the default Accept header value changed to */*.
http.headers.Accept-Encoding 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Accept-Encoding.br 📋Firefox1/26/2016 Safari9/19/2017602
Safari: Unsupported before macOS 10.13 High Sierra.
http.headers.Accept-Encoding.zstd 📋Firefox5/14/2024 Safari2/11/2026638
Safari: Before macOS 26.3 Tahoe, this header value is not sent.
http.headers.Accept-Language 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Accept-Ranges 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Access-Control-Allow-Credentials 📋Safari6/8/2009 Firefox6/30/200922
http.headers.Access-Control-Allow-Headers 📋Safari6/8/2009 Firefox6/30/200922
http.headers.Access-Control-Allow-Headers.wildcard Firefox9/3/2019 Safari9/19/201916
http.headers.Access-Control-Allow-Methods 📋Safari6/8/2009 Firefox6/30/200922
http.headers.Access-Control-Allow-Methods.wildcard Firefox9/3/2019 Safari9/19/201916
http.headers.Access-Control-Allow-Origin 📋Safari6/8/2009 Firefox6/30/200922
http.headers.Access-Control-Expose-Headers 📋Safari6/8/2009 Firefox6/30/200922
http.headers.Access-Control-Expose-Headers.wildcard Firefox9/3/2019 Safari9/19/201916
http.headers.Access-Control-Max-Age 📋Safari6/8/2009 Firefox6/30/200922
http.headers.Access-Control-Request-Headers 📋Safari6/8/2009 Firefox6/30/200922
http.headers.Access-Control-Request-Method 📋Safari6/8/2009 Firefox6/30/200922
http.headers.Age 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Alt-Svc 📋Firefox5/12/2015 Safari9/18/20233051
Firefox: Only supports draft-04Firefox for Android: Only supports draft-04
http.headers.Authorization 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Authorization.Basic 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Authorization.Digest 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Authorization.Digest.md5 Safari6/23/2003 Firefox11/9/2004505
http.headers.Authorization.NTLM Firefox11/9/2004 Safari10/22/20133269
http.headers.Authorization.Negotiate 📋Firefox11/9/2004 Safari10/22/20133269
http.headers.Authorization.authorization_removed_cross_origin 📋Safari10/24/2022 Firefox3/14/2023141
http.headers.Cache-Control 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Cache-Control.immutable Firefox9/20/2016 Safari9/19/2017364
http.headers.Cache-Control.stale-while-revalidate 📋Firefox7/9/2019 Safari9/16/2020435
http.headers.Clear-Site-Data 📋Firefox10/23/2018 Safari9/18/20231791
http.headers.Clear-Site-Data.cache 📋Safari9/18/2023 Firefox4/29/2025589
Chrome: Setting this value may increase response duration (see bug 40233601.Chrome: Setting this value may prevent a page from fully load (see bug 41343050.Chrome Android: Setting this value may increase response duration (see bug 40233601.Chrome Android: Setting this value may prevent a page from fully load (see bug 41343050.Edge: Setting this value may increase response duration (see bug 40233601.Quest Browser: Setting this value may increase response duration (see bug 40233601.Opera: Setting this value may increase response duration (see bug 40233601.Opera: Setting this value may prevent a page from fully load (see bug 41343050.Opera Android: Setting this value may increase response duration (see bug 40233601.Opera Android: Setting this value may prevent a page from fully load (see bug 41343050.Samsung Internet: Setting this value may increase response duration (see bug 40233601.WebView Android: Setting this value may increase response duration (see bug 40233601.WebView Android: Setting this value may prevent a page from fully load (see bug 41343050.
http.headers.Clear-Site-Data.cookies 📋Firefox10/23/2018 Safari9/18/20231791
http.headers.Clear-Site-Data.secure_context_required Firefox10/23/2018 Safari9/18/20231791
http.headers.Clear-Site-Data.storage 📋Firefox10/23/2018 Safari9/18/20231791
http.headers.Clear-Site-Data.wildcard 📋Firefox10/23/2018 Safari9/18/20231791
http.headers.Connection 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Content-Disposition 📋Safari6/23/2003 Firefox11/9/2004505
Chrome: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 352093465.Chrome Android: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 352093465.Firefox: From version 82, if an <a> element's download attribute is set (for a same-origin URL) then the inline directive is ignored. Earlier versions did not match the specification and respected the header directive over the attribute. See bug 1658877.Firefox for Android: From version 82, if an <a> element's download attribute is set (for a same-origin URL) then the inline directive is ignored. Earlier versions did not match the specification and respected the header directive over the attribute. See bug 1658877.Quest Browser: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 352093465.Opera: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 352093465.Opera Android: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 352093465.Safari: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 18384.Safari on iOS: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 18384.Samsung Internet: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 352093465.WebView Android: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 352093465.WebView on iOS: When saving documents, the document title is used instead of the filename parameter if the disposition type is inline. See bug 18384.
http.headers.Content-Encoding 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Content-Encoding.br 📋Firefox1/26/2016 Safari9/19/2017602
Safari: Unsupported before macOS 10.13 High Sierra.
http.headers.Content-Encoding.zstd 📋Firefox5/14/2024 Safari2/11/2026638
Safari: Before macOS 26.3 Tahoe, Safari cannot decode Zstandard responses.
http.headers.Content-Language 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Content-Length 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Content-Length.cors_response_safelist Safari3/25/2019 Firefox3/23/2021729
http.headers.Content-Location 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Content-Range 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Content-Security-Policy 📋Firefox8/6/2013 Safari10/22/201377
Internet Explorer: Only supporting 'sandbox' directive.
http.headers.Content-Security-Policy.base-uri 📋Firefox1/13/2015 Safari9/20/2016616
http.headers.Content-Security-Policy.child-src 📋Firefox3/8/2016 Safari9/20/2016196
http.headers.Content-Security-Policy.connect-src 📋Safari10/22/2013 Firefox11/15/20161120
Firefox: Before Firefox 50, ping attributes of <a> elements weren't covered by connect-src.
http.headers.Content-Security-Policy.default-src 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.font-src 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.form-action 📋Firefox2/24/2015 Safari9/20/2016574
http.headers.Content-Security-Policy.frame-ancestors 📋Safari9/20/2016 Firefox1/23/2018490
Firefox: Before Firefox 58, frame-ancestors is ignored in Content-Security-Policy-Report-Only.Firefox for Android: Before Firefox for Android 58, frame-ancestors is ignored in Content-Security-Policy-Report-Only.
http.headers.Content-Security-Policy.frame-src 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.img-src 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.manifest-src 📋Firefox9/22/2015 Safari9/19/2017728
http.headers.Content-Security-Policy.media-src 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.meta-element-support Safari10/22/2013 Firefox3/8/2016868
http.headers.Content-Security-Policy.object-src 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.report-sample Firefox10/23/2018 Safari3/14/20221238
http.headers.Content-Security-Policy.report-to 📋Safari3/27/2023 Firefox9/3/2024526
http.headers.Content-Security-Policy.report-uri 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.sandbox 📋Safari10/22/2013 Firefox11/15/20161120
http.headers.Content-Security-Policy.script-src 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.script-src.external_scripts 📋Safari7/20/2022 Firefox8/1/2023377
http.headers.Content-Security-Policy.script-src.wasm-unsafe-eval Firefox6/28/2022 Safari9/12/202276
http.headers.Content-Security-Policy.script-src-attr 📋Safari3/14/2022 Firefox12/13/2022274
http.headers.Content-Security-Policy.script-src-elem 📋Safari3/14/2022 Firefox12/13/2022274
http.headers.Content-Security-Policy.strict-dynamic Firefox3/7/2017 Safari3/14/20221833
http.headers.Content-Security-Policy.style-src 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Security-Policy.style-src-attr 📋Safari3/14/2022 Firefox12/13/2022274
http.headers.Content-Security-Policy.style-src-elem 📋Firefox12/13/2022 Safari12/12/20251095
Safari: The style-src-elem directive was parsed, but had no effect. See bug 276931.Safari on iOS: The style-src-elem directive was parsed, but had no effect. See bug 276931.WebView on iOS: The style-src-elem directive was parsed, but had no effect. See bug 276931.
http.headers.Content-Security-Policy.unsafe-hashes Safari3/14/2022 Firefox1/17/2023309
http.headers.Content-Security-Policy.upgrade-insecure-requests 📋Firefox11/3/2015 Safari3/27/2017510
http.headers.Content-Security-Policy.worker-src 📋Firefox1/23/2018 Safari5/16/20221574
Chrome: Chrome 59 and higher skips the deprecated child-src directive.Chrome Android: Chrome Android 59 and higher skips the deprecated child-src directive.Quest Browser: Quest Browser 5.0 and higher skips the deprecated child-src directive.Opera: Opera 46 and higher skips the deprecated child-src directive.Opera Android: Opera Android 43 and higher skips the deprecated child-src directive.WebView Android: WebView Android 59 and higher skips the deprecated child-src directive.
http.headers.Content-Security-Policy.worker_support Safari9/20/2016 Firefox11/15/201656
http.headers.Content-Security-Policy-Report-Only 📋Firefox8/6/2013 Safari10/22/201377
http.headers.Content-Type 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Cookie 📋Safari6/23/2003 Firefox11/9/2004505
Safari: Cookies with Secure flag are not sent to unsecured http://localhost/ endpoints. See bug 281149.Safari on iOS: Cookies with Secure flag are not sent to unsecured http://localhost/ endpoints. See bug 281149.WebView on iOS: Cookies with Secure flag are not sent to unsecured http://localhost/ endpoints. See bug 281149.
http.headers.Cross-Origin-Embedder-Policy 📋Firefox7/28/2020 Safari12/13/2021503
http.headers.Cross-Origin-Opener-Policy 📋Firefox7/28/2020 Safari12/13/2021503
http.headers.Cross-Origin-Resource-Policy 📋Safari9/17/2018 Firefox3/10/2020540
Chrome: Until version 75, downloads for files with this header would fail in Chrome. See bug 41452948.Chrome: From version 80 to 85, linearized PDFs served inline with this header fail to render properly. See bug 40127935. From version 86, partial PDF loading is disabled.Chrome Android: Until version 75, downloads for files with this header would fail in Chrome Android. See bug 41452948.Chrome Android: From version 80 to 85, linearized PDFs served inline with this header fail to render properly. See bug 40127935. From version 86, partial PDF loading is disabled.Quest Browser: Until version 7.0, downloads for files with this header would fail in Quest Browser. See bug 41452948.Quest Browser: From version 9.0 to 85, linearized PDFs served inline with this header fail to render properly. See bug 40127935. From version 12.0, partial PDF loading is disabled.Opera: Until version 62, downloads for files with this header would fail in Opera. See bug 41452948.Opera: From version 67 to 85, linearized PDFs served inline with this header fail to render properly. See bug 40127935. From version 72, partial PDF loading is disabled.Opera Android: Until version 54, downloads for files with this header would fail in Opera Android. See bug 41452948.Opera Android: From version 57 to 85, linearized PDFs served inline with this header fail to render properly. See bug 40127935. From version 61, partial PDF loading is disabled.WebView Android: Until version 75, downloads for files with this header would fail in WebView Android. See bug 41452948.WebView Android: From version 80 to 85, linearized PDFs served inline with this header fail to render properly. See bug 40127935. From version 86, partial PDF loading is disabled.
http.headers.Date 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.ETag 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Expires 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.From 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Host 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.If-Match 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.If-Modified-Since 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.If-None-Match 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.If-Range 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.If-Unmodified-Since 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Keep-Alive 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Last-Modified 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Link 📋Safari9/18/2023 Firefox11/21/202364
http.headers.Link.fetchpriority 📋Safari12/11/2023 Firefox10/29/2024323
http.headers.Location 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Origin 📋Safari6/23/2003 Firefox10/22/20195965
Edge: Not sent with POST requestsFirefox: Not sent with POST requests, see bug 446344.Firefox for Android: Not sent with POST requests, see bug 446344.
http.headers.Pragma 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Proxy-Authenticate 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Range 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Range.cors_safe Safari9/12/2022 Firefox8/29/2023351
http.headers.Referer 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Referer.length_limit_4096B Firefox10/22/2019 Safari9/16/2020330
http.headers.Referrer-Policy 📋Firefox11/15/2016 Safari4/12/2018513
http.headers.Referrer-Policy.default_strict-origin-when-cross-origin Firefox3/23/2021 Safari9/20/2021181
http.headers.Referrer-Policy.same-origin Firefox3/7/2017 Safari4/12/2018401
http.headers.Referrer-Policy.strict-origin Firefox3/7/2017 Safari4/12/2018401
http.headers.Referrer-Policy.strict-origin-when-cross-origin Firefox3/7/2017 Safari4/12/2018401
http.headers.Refresh 📋Safari6/23/2003 Firefox11/9/2004505
Firefox: From version 136 the HTTP Referer header is sent following a refresh that redirects to another page (if permitted)Firefox for Android: From version 136 the HTTP Referer header is sent following a refresh that redirects to another page (if permitted)
http.headers.Reporting-Endpoints 📋Safari3/27/2023 Firefox9/3/2024526
http.headers.Sec-Fetch-Dest 📋Firefox7/13/2021 Safari3/27/2023622
http.headers.Sec-Fetch-Mode 📋Firefox7/13/2021 Safari3/27/2023622
http.headers.Sec-Fetch-Site 📋Firefox7/13/2021 Safari3/27/2023622
http.headers.Sec-WebSocket-Accept 📋Firefox3/13/2012 Safari7/25/2012134
http.headers.Sec-WebSocket-Extensions 📋Firefox3/13/2012 Safari7/25/2012134
http.headers.Sec-WebSocket-Key 📋Firefox3/13/2012 Safari7/25/2012134
http.headers.Sec-WebSocket-Protocol 📋Firefox3/13/2012 Safari7/25/2012134
http.headers.Sec-WebSocket-Version 📋Firefox3/13/2012 Safari7/25/2012134
http.headers.Server 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Server-Timing 📋Firefox6/26/2018 Safari3/27/20231735
http.headers.Service-Worker 📋Firefox1/26/2016 Safari4/12/2018807
http.headers.Service-Worker-Allowed 📋Firefox8/11/2015 Safari4/12/2018975
http.headers.Set-Cookie 📋Safari6/23/2003 Firefox11/9/2004505
Safari: Cookies with Secure flag are not sent to unsecured http://localhost/ endpoints. See bug 281149.Safari on iOS: Cookies with Secure flag are not sent to unsecured http://localhost/ endpoints. See bug 281149.WebView on iOS: Cookies with Secure flag are not sent to unsecured http://localhost/ endpoints. See bug 281149.
http.headers.Set-Cookie.HttpOnly Firefox6/17/2008 Safari6/7/2010720
http.headers.Set-Cookie.Max-Age Safari6/23/2003 Firefox11/9/2004505
http.headers.Set-Cookie.Partitioned 📋Firefox7/22/2025 Safari12/12/2025143
http.headers.Set-Cookie.SameSite 📋Firefox5/9/2018 Safari9/19/2019498
Safari: Safari 13 on macOS 10.14 (Mojave), treats SameSite=None and invalid values as Strict. This is fixed in version 10.15 (Catalina) and later.Safari: Treats SameSite=None and invalid values as Strict in macOS before 10.15 Catalina. See bug 198181.Safari on iOS: Treats SameSite=None and invalid values as Strict in iOS before 13. See bug 198181.WebView on iOS: Treats SameSite=None and invalid values as Strict in iOS before 13. See bug 198181.
http.headers.Set-Cookie.SameSite.Lax Firefox5/9/2018 Safari9/17/2018131
http.headers.Set-Cookie.SameSite.None Firefox5/9/2018 Safari9/19/2019498
Chrome: Rejects cookies with SameSite=None. See SameSite=None: Known Incompatible Clients.Chrome Android: Rejects cookies with SameSite=None. See SameSite=None: Known Incompatible Clients.Quest Browser: Rejects cookies with SameSite=None. See SameSite=None: Known Incompatible Clients.Opera: Rejects cookies with SameSite=None. See SameSite=None: Known Incompatible Clients.Opera Android: Rejects cookies with SameSite=None. See SameSite=None: Known Incompatible Clients.Safari: Not supported before macOS version 10.15 (Catalina).Samsung Internet: Rejects cookies with SameSite=None. See SameSite=None: Known Incompatible Clients.WebView Android: Rejects cookies with SameSite=None. See SameSite=None: Known Incompatible Clients.
http.headers.Set-Cookie.SameSite.Strict Firefox5/9/2018 Safari9/17/2018131
http.headers.Set-Cookie.host_secure_prefixes Firefox11/15/2016 Safari9/19/20191038
http.headers.SourceMap 📋Safari10/22/2013 Firefox8/8/20171386
Chrome: Not supported for ECMAScript Modules (<script type="module">). See bug 40854862.Chrome Android: Not supported for ECMAScript Modules (<script type="module">). See bug 40854862.Edge: Not supported for ECMAScript Modules (<script type="module">). See bug 40854862.Quest Browser: Not supported for ECMAScript Modules (<script type="module">). See bug 40854862.Opera: Not supported for ECMAScript Modules (<script type="module">). See bug 40854862.Opera Android: Not supported for ECMAScript Modules (<script type="module">). See bug 40854862.Samsung Internet: Not supported for ECMAScript Modules (<script type="module">). See bug 40854862.WebView Android: Not supported for ECMAScript Modules (<script type="module">). See bug 40854862.
http.headers.Strict-Transport-Security 📋Firefox3/22/2011 Safari10/22/2013945
http.headers.TE 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Timing-Allow-Origin 📋Firefox3/8/2016 Safari9/19/2017560
http.headers.Transfer-Encoding 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Upgrade 📋Safari6/7/2010 Firefox8/16/2011435
http.headers.Upgrade-Insecure-Requests 📋Firefox8/2/2016 Safari3/27/2017237
http.headers.User-Agent 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Vary 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.Via 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.WWW-Authenticate 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.WWW-Authenticate.Basic 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.WWW-Authenticate.Digest 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.WWW-Authenticate.Digest.md5 Safari6/23/2003 Firefox11/9/2004505
http.headers.WWW-Authenticate.NTLM Firefox11/9/2004 Safari10/22/20133269
http.headers.WWW-Authenticate.Negotiate 📋Firefox11/9/2004 Safari10/22/20133269
http.headers.Warning 📋Safari6/23/2003 Firefox11/9/2004505
http.headers.X-Content-Type-Options 📋Firefox11/15/2016 Safari9/19/2017308
Chrome: Not supported for stylesheets.Chrome Android: Not supported for stylesheets.Opera: Not supported for stylesheets.Opera Android: Not supported for stylesheets.Samsung Internet: Not supported for stylesheets.WebView Android: Not supported for stylesheets.
http.headers.X-Frame-Options 📋Safari6/8/2009 Firefox3/22/2011652
http.headers.X-Frame-Options.SAMEORIGIN Safari6/8/2009 Firefox3/22/2011652
Chrome: Starting in Chrome 61, this applies to all of a frame's ancestors.Chrome Android: Starting in Chrome Android 61, this applies to all of a frame's ancestors.Firefox: Starting in Firefox 59, this applies to all of a frame's ancestors.Firefox for Android: Starting in Firefox for Android 59, this applies to all of a frame's ancestors.Quest Browser: Starting in Quest Browser 5.0, this applies to all of a frame's ancestors.Opera: Starting in Opera 48, this applies to all of a frame's ancestors.Opera Android: Starting in Opera Android 45, this applies to all of a frame's ancestors.Samsung Internet: Starting in Samsung Internet 8.0, this applies to all of a frame's ancestors.WebView Android: Starting in WebView Android 61, this applies to all of a frame's ancestors.
http.methods.CONNECT 📋Safari6/23/2003 Firefox11/9/2004505
http.methods.DELETE 📋Safari6/23/2003 Firefox11/9/2004505
http.methods.GET 📋Safari6/23/2003 Firefox11/9/2004505
http.methods.HEAD 📋Safari6/23/2003 Firefox11/9/2004505
http.methods.OPTIONS 📋Safari6/23/2003 Firefox11/9/2004505
http.methods.POST 📋Safari6/23/2003 Firefox11/9/2004505
http.methods.PUT 📋Safari6/23/2003 Firefox11/9/2004505
http.mixed-content 📋Firefox8/6/2013 Safari3/21/2016958
http.mixed-content.blockable_mixed_content 📋Firefox8/6/2013 Safari3/21/2016958
Chrome: From version 79 blocks iframes, scripts, and stylesheets.Chrome Android: From version 79 blocks iframes, scripts, and stylesheets.Edge: From version 79 blocks iframes, scripts, and stylesheets.Quest Browser: From version 8.0 blocks iframes, scripts, and stylesheets.Opera: From version 66 blocks iframes, scripts, and stylesheets.Opera Android: From version 57 blocks iframes, scripts, and stylesheets.Samsung Internet: From version 12.0 blocks iframes, scripts, and stylesheets.WebView Android: From version 79 blocks iframes, scripts, and stylesheets.
http.status.103 📋Safari9/18/2023 Firefox11/21/202364
Chrome: Supported in HTTP/2 and later only.Chrome Android: Supported in HTTP/2 and later only.Edge: Supported in HTTP/2 and later only.Quest Browser: Supported in HTTP/2 and later only.Opera: Supported in HTTP/2 and later only.Opera Android: Supported in HTTP/2 and later only.Safari: Supported in HTTP/2 and later only.Safari on iOS: Supported in HTTP/2 and later only.Samsung Internet: Supported in HTTP/2 and later only.WebView Android: Supported in HTTP/2 and later only.WebView on iOS: Supported in HTTP/2 and later only.
http.status.103.preconnect Safari9/18/2023 Firefox11/21/202364
http.status.308 📋Firefox7/17/2012 Safari10/22/2013462
Internet Explorer: Does not work below Windows 10.