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 SafariNot in Chrome
In Safari 16
In Chrome 144

Unstable APIs

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

Raw Data

Quick Links:

HTML Data

API First Browser Date Days in Limbo Notes
html.elements.a.attributionsourceid 📋Safari4/26/20211970
html.elements.a.attributionsrc 📋Chrome5/14/2024856
html.elements.a.hreftranslate Chrome4/7/20202354
html.elements.a.referrerpolicy.no-referrer-when-downgrade Chrome5/25/20163767
html.elements.a.referrerpolicy.origin-when-cross-origin Chrome5/25/20163767
html.elements.a.referrerpolicy.unsafe-url Chrome5/25/20163767
html.elements.a.target.unfencedTop Chrome7/18/20231157
html.elements.area.referrerpolicy.no-referrer-when-downgrade Chrome5/25/20163767
html.elements.area.referrerpolicy.origin-when-cross-origin Chrome5/25/20163767
html.elements.area.referrerpolicy.unsafe-url Chrome5/25/20163767
html.elements.audio.controlslist 📋Chrome4/19/20173438
html.elements.fencedframe 📋Chrome7/18/20231157
html.elements.fencedframe.allow 📋Chrome7/18/20231157
html.elements.fencedframe.height 📋Chrome7/18/20231157
html.elements.fencedframe.width 📋Chrome7/18/20231157
html.elements.form.autocomplete.webauthn 📋Chrome11/29/20221388
html.elements.iframe.allow.accelerometer 📋Chrome4/17/20183075
html.elements.iframe.allow.ambient-light-sensor 📋Chrome4/17/20183075
html.elements.iframe.allow.attribution-reporting 📋Chrome9/12/20231101
html.elements.iframe.allow.autoplay 📋Chrome1/23/20183159
html.elements.iframe.allow.bluetooth 📋Chrome8/2/20221507
html.elements.iframe.allow.browsing-topics Chrome7/18/20231157
html.elements.iframe.allow.compute-pressure 📋Chrome5/14/2024856
html.elements.iframe.allow.cross-origin-isolated 📋Chrome11/17/20202130
html.elements.iframe.allow.document-domain 📋Chrome1/23/20183159
html.elements.iframe.allow.encrypted-media 📋Chrome1/23/20183159
html.elements.iframe.allow.fullscreen 📋Chrome10/17/20173257
html.elements.iframe.allow.geolocation 📋Chrome1/23/20183159
html.elements.iframe.allow.gyroscope 📋Chrome4/17/20183075
html.elements.iframe.allow.hid 📋Chrome3/2/20212025
html.elements.iframe.allow.identity-credentials-get 📋Chrome2/7/20231318
html.elements.iframe.allow.idle-detection 📋Chrome9/21/20211822
html.elements.iframe.allow.local-fonts 📋Chrome6/21/20221549
html.elements.iframe.allow.magnetometer 📋Chrome4/17/20183075
html.elements.iframe.allow.midi 📋Chrome1/23/20183159
html.elements.iframe.allow.otp-credentials 📋Chrome8/31/20211843
html.elements.iframe.allow.payment 📋Chrome7/25/20173341
html.elements.iframe.allow.picture-in-picture 📋Chrome12/4/20182844
html.elements.iframe.allow.publickey-credentials-get 📋Chrome7/27/20202243
html.elements.iframe.allow.serial 📋Chrome3/2/20212025
html.elements.iframe.allow.storage-access 📋Chrome5/2/20231234
html.elements.iframe.allow.usb 📋Chrome7/25/20173341
html.elements.iframe.allow.web-share 📋Chrome10/20/20202158
Firefox: Firefox recognizes the web-share permissions policy, but this has no effect in versions of Firefox that do not support the share() method.Firefox for Android: Firefox for Android recognizes the web-share permissions policy, but this has no effect in versions of Firefox for Android that do not support the share() method.
html.elements.iframe.allow.wildcards Chrome11/29/20221388
html.elements.iframe.allow.window-management 📋Chrome3/29/20221633
html.elements.iframe.allow.xr-spatial-tracking 📋Chrome12/10/20192473
html.elements.iframe.allowpaymentrequest Chrome7/25/20173341
html.elements.iframe.browsingtopics Chrome7/18/20231157
html.elements.iframe.credentialless 📋Chrome2/7/20231318
html.elements.iframe.csp 📋Chrome9/5/20173299
html.elements.iframe.referrerpolicy.no-referrer-when-downgrade Chrome5/25/20163767
html.elements.iframe.referrerpolicy.origin-when-cross-origin Chrome5/25/20163767
html.elements.iframe.referrerpolicy.unsafe-url Chrome5/25/20163767
html.elements.iframe.sandbox.allow-orientation-lock 📋Chrome7/24/20182977
html.elements.iframe.sandbox.allow-presentation 📋Chrome8/31/20163669
html.elements.iframe.sandbox.allow-top-navigation-to-custom-protocols 📋Safari9/12/20221466
html.elements.img.attributionsrc 📋Chrome5/14/2024856
html.elements.img.referrerpolicy.no-referrer-when-downgrade Chrome5/25/20163767
html.elements.img.referrerpolicy.origin-when-cross-origin Chrome5/25/20163767
html.elements.img.referrerpolicy.unsafe-url Chrome5/25/20163767
html.elements.img.sizes.auto 📋Chrome6/11/2024828
html.elements.input.type_month 📋Chrome6/26/20125196
Safari: The input type is recognized, but there is no month-specific control. See bug 200416.
html.elements.input.type_week 📋Chrome6/26/20125196
html.elements.link.referrerpolicy.no-referrer-when-downgrade Chrome5/25/20163767
html.elements.link.referrerpolicy.origin-when-cross-origin Chrome5/25/20163767
html.elements.link.referrerpolicy.unsafe-url Chrome5/25/20163767
html.elements.link.rel.expect 📋Chrome4/16/2024884
html.elements.link.rel.prerender Chrome8/2/20115525
html.elements.meta.name.application-title Chrome3/4/2025562
html.elements.script.attributionsrc 📋Chrome5/14/2024856
html.elements.script.referrerpolicy.no-referrer-when-downgrade Chrome10/16/20182893
html.elements.script.referrerpolicy.origin-when-cross-origin Chrome10/16/20182893
html.elements.script.referrerpolicy.unsafe-url Chrome10/16/20182893
html.elements.script.type.importmap.multiple_import_maps 📋Chrome2/4/2025590
html.elements.script.type.speculationrules 📋Chrome1/10/20231346
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.
html.elements.script.type.speculationrules.eagerness Chrome1/23/2024968
html.elements.script.type.speculationrules.expects_no_vary_search Chrome7/23/2024786
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.
html.elements.script.type.speculationrules.prefetch Chrome2/7/20231318
html.elements.script.type.speculationrules.prerender Chrome9/2/20221476
html.elements.script.type.speculationrules.referrer_policy Chrome3/7/20231290
html.elements.script.type.speculationrules.relative_to Chrome1/23/2024968
html.elements.script.type.speculationrules.requires Chrome2/7/20231318
html.elements.script.type.speculationrules.requires.anonymous-client-ip-when-cross-origin Chrome2/7/20231318
html.elements.script.type.speculationrules.source_optional Chrome2/20/2024940
html.elements.script.type.speculationrules.urls Chrome1/10/20231346
html.elements.script.type.speculationrules.where Chrome1/23/2024968
html.elements.summary.display_list_item Chrome3/2/20212025
html.elements.td.rowspan.rowspan_zero Chrome3/6/20183117
html.elements.template.shadowrootclonable 📋Chrome4/16/2024884
html.elements.template.shadowrootdelegatesfocus 📋Chrome3/19/2024912
html.elements.template.shadowrootserializable 📋Chrome5/14/2024856
html.elements.textarea.autocomplete.webauthn 📋Chrome11/29/20221388
html.elements.textarea.wrap.hard Chrome12/13/20115392
html.elements.video.controlslist 📋Chrome4/19/20173438
html.global_attributes.autocapitalize 📋Chrome5/19/20154139
html.global_attributes.autocorrect 📋Safari4/26/20211970
Safari: Takes values of true/false (instead of on/off).Safari: Allowed on <input type='password'> elements.Safari on iOS: Takes values of true/false (instead of on/off).Safari on iOS: Allowed on <input type='password'> elements.
html.global_attributes.hidden.until-found 📋Chrome5/24/20221577
html.global_attributes.is 📋Chrome5/29/20183033
html.global_attributes.virtualkeyboardpolicy 📋Chrome9/21/20211822
html.manifest.background_color 📋Chrome10/13/20153992
html.manifest.description 📋Chrome1/19/20212067
Firefox for Android: The property parses, but has no effect.
html.manifest.display.fullscreen 📋Chrome11/18/20144321
html.manifest.display.minimal-ui 📋Chrome11/18/20144321
html.manifest.display_override 📋Chrome3/2/20212025
Chrome: display_override and/or display are required for a web app to be installable.Chrome Android: display_override and/or display are required for a web app to be installable.Edge: display_override and/or display are required for a web app to be installable.Quest Browser: display_override and/or display are required for a web app to be installable.Opera: display_override and/or display are required for a web app to be installable.Opera Android: display_override and/or display are required for a web app to be installable.Samsung Internet: display_override and/or display are required for a web app to be installable.
html.manifest.display_override.tabbed 📋Chrome6/11/2024828
html.manifest.display_override.window-controls-overlay 📋Chrome9/2/20221476
html.manifest.file_handlers 📋Chrome5/24/20221577
html.manifest.launch_handler 📋Chrome2/7/20231318
html.manifest.launch_handler.client_mode 📋Chrome2/7/20231318
html.manifest.note_taking 📋Chrome10/19/20211794
html.manifest.note_taking.new_note_url 📋Chrome10/19/20211794
html.manifest.orientation 📋Chrome11/18/20144321
html.manifest.protocol_handlers 📋Chrome11/15/20211767
html.manifest.protocol_handlers.protocol 📋Chrome11/15/20211767
html.manifest.protocol_handlers.url 📋Chrome11/15/20211767
html.manifest.serviceworker Chrome10/16/20182893
html.manifest.serviceworker.scope Chrome10/16/20182893
html.manifest.serviceworker.src Chrome10/16/20182893
html.manifest.serviceworker.use_cache Chrome10/16/20182893
html.manifest.share_target 📋Chrome3/2/20212025
Firefox for Android: The property parses, but has no effect.

JS Data

API First Browser Date Days in Limbo Notes
javascript.builtins.Atomics.pause 📋Chrome2/4/2025590
javascript.builtins.DataView.getFloat16 📋Safari12/11/2024645
javascript.builtins.DataView.setFloat16 📋Safari12/11/2024645
javascript.builtins.Error.cause.displayed_in_console Chrome5/14/2024856
javascript.builtins.Error.serializable_object 📋Chrome9/10/20192564
Firefox: Version 103 serialized properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 adds serialization of stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 adds serialization of stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serialized properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 adds serialization of stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 adds serialization of stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.EvalError.serializable_object 📋Chrome9/10/20192564
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.Float16Array 📋Safari12/11/2024645
javascript.builtins.Float16Array.Float16Array 📋Safari12/11/2024645
javascript.builtins.Intl.PluralRules.PluralRules.options_parameter.options_roundingIncrement_parameter Safari12/11/20231011
javascript.builtins.Iterator.Iterator 📋Chrome2/20/2024940
javascript.builtins.Iterator.drop 📋Chrome2/20/2024940
javascript.builtins.Iterator.every 📋Chrome2/20/2024940
javascript.builtins.Iterator.filter 📋Chrome2/20/2024940
javascript.builtins.Iterator.find 📋Chrome2/20/2024940
javascript.builtins.Iterator.flatMap 📋Chrome2/20/2024940
javascript.builtins.Iterator.forEach 📋Chrome2/20/2024940
javascript.builtins.Iterator.from 📋Chrome2/20/2024940
javascript.builtins.Iterator.map 📋Chrome2/20/2024940
javascript.builtins.Iterator.reduce 📋Chrome2/20/2024940
javascript.builtins.Iterator.some 📋Chrome2/20/2024940
javascript.builtins.Iterator.take 📋Chrome2/20/2024940
javascript.builtins.Iterator.toArray 📋Chrome2/20/2024940
javascript.builtins.JSON.isRawJSON 📋Chrome5/30/20231206
javascript.builtins.JSON.parse.reviver_parameter_context_argument 📋Chrome5/30/20231206
javascript.builtins.JSON.rawJSON 📋Chrome5/30/20231206
javascript.builtins.Math.f16round 📋Safari12/11/2024645
javascript.builtins.RangeError.serializable_object 📋Chrome9/10/20192564
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.ReferenceError.serializable_object 📋Chrome9/10/20192564
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.RegExp.escape 📋Safari12/11/2024645
javascript.builtins.SyntaxError.serializable_object 📋Chrome9/10/20192564
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.TypeError.serializable_object 📋Chrome9/10/20192564
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.URIError.serializable_object 📋Chrome9/10/20192564
Firefox: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).Firefox for Android: Version 103 serializable properties: name, message, cause, fileName, lineNumber and columnNumber.Firefox for Android: Version 104 also serializes stack in the main thread (window.postMessage() and structuredClone()).Firefox for Android: Version 110 also serializes stack in workers (worker.postMessage() and structuredClone()).
javascript.builtins.Uint8Array.fromBase64 📋Safari12/11/2024645
javascript.builtins.Uint8Array.fromHex 📋Safari12/11/2024645
javascript.builtins.Uint8Array.setFromBase64 📋Safari12/11/2024645
javascript.builtins.Uint8Array.setFromHex 📋Safari12/11/2024645
javascript.builtins.Uint8Array.toBase64 📋Safari12/11/2024645
javascript.builtins.Uint8Array.toHex 📋Safari12/11/2024645
javascript.regular_expressions.modifier 📋Chrome5/14/2024856
javascript.statements.import.import_attributes.type_css Chrome3/19/2024912