mdn/browser-compat-data

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Browser compatibility data for Web technologies as displayed on MDN

Stars: 5.8k
Forks: 2.6k
Open beginner issues: 4
Indexed issues: 350
Avg merge: 1d 21h
Merged PRs (30d): 186

Dominant language: JSON
License: CC0-1.0
Last GitHub push: Sep 18, 2026
Latest indexed: Sep 19, 2026
Contributing guide: Contributing guide
Code of conduct: Code of conduct
Beginner labels: help wanted good first issue

Beginner friendly Everything

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350 issues indexed so far

css.properties.display.is_transitionable — Safari 27 disables display transitions for popovers and <dialog> Open

data:css needs triage

Difficulty 2/5 1-3 hours Newbie friendliness 82/100

mdn/browser-compat-data#30560 · Opened Sep 17, 2026
api.PublicKeyCredential - missing platform-specific compatibility for desktop operating systems Open

data:api needs triage

Difficulty 4/5 3-5 days Newbie friendliness 50/100

mdn/browser-compat-data#30559 · 1 comment · Opened Sep 17, 2026
`webdriver.bidi.session.new` - multiple sessions should have a behavioral subfeature Open

blocked data:webdriver

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

mdn/browser-compat-data#30540 · 2 comments · Opened Sep 15, 2026
css.types.line-width - Missing compatibility data Open

browser:multiple data:css needs collector test p3

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mdn/browser-compat-data#30533 · 2 comments · Opened Sep 15, 2026
margin-trim is only partially supported in Safari Open

browser:safari data:css

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

mdn/browser-compat-data#30528 · 3 comments · Opened Sep 15, 2026
[meta] PR Review Companion improvements Open

enhancement infra

Difficulty 5/5 Over a week Newbie friendliness 35/100

mdn/browser-compat-data#30485 · Opened Sep 11, 2026
Alert reviewers when most but not all keys with the same web-features tag are modified in a PR Open

enhancement infra

Difficulty 5/5 Over a week Newbie friendliness 45/100

mdn/browser-compat-data#30483 · 1 comment · 2 reactions · Opened Sep 11, 2026
html.elements.dialog - closedby=any bugs for touch Open

browser:chrome browser:firefox data:html p3

Difficulty 2/5 1-3 hours Newbie friendliness 58/100

mdn/browser-compat-data#30474 · 1 comment · Opened Sep 11, 2026
`html.global_attributes.focusgroup` etc. - missing data Open

browser:chrome data:html needs collector test

Difficulty 2/5 1-3 hours Newbie friendliness 70/100

mdn/browser-compat-data#30468 · 1 comment · Opened Sep 10, 2026
`flex-start` and `flex-end` - No support data for these values Open

browser:multiple data:css p2

mdn/browser-compat-data#30410 · 2 comments · 1 assignee · Opened Sep 3, 2026
Wasm js-types proposal - missing Open

browser:multiple data:wasm p3

Difficulty 3/5 1-2 days Newbie friendliness 68/100

mdn/browser-compat-data#30393 · Opened Sep 2, 2026
Add api.HTMLElement* constructor data Open

data:api

Difficulty 5/5 Over a week Newbie friendliness 35/100

mdn/browser-compat-data#30380 · 1 comment · Opened Sep 1, 2026
<line-width> values for gap, column-gap, and row-gap Open

data:css needs collector test p3

Difficulty 2/5 1-3 hours Newbie friendliness 78/100

mdn/browser-compat-data#30402 · Opened Sep 1, 2026
javascript.builtins.Temporal - Safari `impl_url` references outdated WebKit umbrella bug Open

browser:safari data:js

Difficulty 3/5 1-2 days Newbie friendliness 58/100

mdn/browser-compat-data#30337 · Opened Aug 26, 2026
css.selectors.-webkit-meter-bar - Seems to be incorrectly marked as "deprecated" Open

data:css meeting agenda

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

mdn/browser-compat-data#30317 · 1 comment · Opened Aug 24, 2026
javascript.operators.import - don't cache HTTP errors Open

browser:multiple data:js p3

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

mdn/browser-compat-data#30304 · 1 comment · 1 reaction · Opened Aug 23, 2026
Label `partial_implementation` data PRs Open

enhancement infra

mdn/browser-compat-data#30261 · 1 reaction · 1 assignee · Opened Aug 18, 2026
webextensions.api.runtime.onMessage - Respond with Promise is supported since Chromium 148 Open

data:webext p3

Difficulty 2/5 1-3 hours Newbie friendliness 70/100

mdn/browser-compat-data#30194 · 2 comments · Opened Aug 7, 2026
api.fetch - Firefox is not compatible because does not fulfil the specification because of bug https://bugzilla.mozilla.org/show_bug.cgi?id=1629773 Open

data:api info needed

Difficulty 2/5 1-3 hours Newbie friendliness 55/100

mdn/browser-compat-data#30185 · 1 comment · Opened Aug 6, 2026
api.ShadowRoot.slotAssignment - `named` value not supported in Chromium 86 Open

data:api needs collector test

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

mdn/browser-compat-data#30182 · 1 comment · Opened Aug 6, 2026
api.fetch - `signal` property is supported by Bun Open

browser:bun data:api p3

Difficulty 2/5 1-3 hours Newbie friendliness 75/100

mdn/browser-compat-data#30151 · 3 comments · 1 reaction · Opened Aug 2, 2026
css.types.image - missing data for `image(<color>)` Open

data:css p3

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mdn/browser-compat-data#30144 · Opened Jul 30, 2026
api.RTCInboundRtpStreamStats.totalFreezesDuration - Supported in Chrome/Edge/Safari iOS per wpt.fyi Open

browser:multiple data:api needs collector test needs research

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mdn/browser-compat-data#30039 · 1 comment · Opened Jul 13, 2026
Verify and consolidate feature flags across BCD Open

browser:multiple early features

Difficulty 5/5 Over a week Newbie friendliness 35/100

mdn/browser-compat-data#30010 · 3 comments · Opened Jul 8, 2026
api.WGSLLanguageFeatures - unrestricted_pointer_parameters is supported in safari Open

browser:safari data:api needs collector test p3

Difficulty 2/5 1-3 hours Newbie friendliness 72/100

mdn/browser-compat-data#29989 · Opened Jul 6, 2026
css.properties.column-rule-color - wrong spec and missing feature Open

data:css meeting agenda needs collector test p3

Difficulty 2/5 1-3 hours Newbie friendliness 64/100

mdn/browser-compat-data#29959 · 4 comments · Opened Jul 1, 2026
CSS random() changed syntax Open

data:css meeting agenda

Difficulty 2/5 1-3 hours Newbie friendliness 58/100

mdn/browser-compat-data#29954 · 1 comment · Opened Jun 30, 2026
manifests.webapp.share_target - Chromium doesn't support it on Linux Open

browser:chrome data:manifests platform limitation

Difficulty 2/5 1-3 hours Newbie friendliness 58/100

mdn/browser-compat-data#29889 · 5 comments · Opened Jun 20, 2026
Update data guideline: Parameters and parameter object features Open

docs:guidelines

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mdn/browser-compat-data#29856 · 2 comments · Opened Jun 16, 2026
Add workerd (Cloudflare Workers open-source runtime) as a server runtime in BCD Open

data:browsers enhancement meeting agenda

Difficulty 5/5 Over a week Newbie friendliness 35/100

mdn/browser-compat-data#29761 · 3 comments · 1 reaction · Opened May 27, 2026
svg.elements.textPath - <Missing lengthAdjust data> Open

browser:multiple data:svg info needed

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mdn/browser-compat-data#29670 · 1 comment · Opened May 13, 2026
Use NodeBB JSON API instead of RSS for Opera release detection Open

infra

Difficulty 4/5 3-5 days Newbie friendliness 55/100

mdn/browser-compat-data#29658 · Opened May 12, 2026
api.Element.requestFullscreen — WKWebView support differs from Safari data Open

browser:safari_ios data:api info needed

Difficulty 4/5 3-5 days Newbie friendliness 45/100

mdn/browser-compat-data#29654 · 4 comments · 1 reaction · Opened May 11, 2026
css.types.basic-shape.circle - Values `closest-corner` and `farthest-corner` are not supported by some browsers yet Open

browser:multiple data:css needs collector test

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mdn/browser-compat-data#29634 · Opened May 8, 2026
api.Document.ariaNotify - Firefox should also be marked as partial Open

acd browser:multiple data:api p3 platform limitation

Difficulty 4/5 3-5 days Newbie friendliness 38/100

mdn/browser-compat-data#29610 · 3 comments · Opened May 5, 2026
javascript.builtins.String.substr - No spec level deprecation Open

javascript p3

Difficulty 4/5 3-5 days Newbie friendliness 48/100

mdn/browser-compat-data#29608 · 1 comment · Opened May 5, 2026
Survey existing data conventions for method parameters, especially parameter objects Open

good first issue help wanted

Difficulty 4/5 3-5 days Newbie friendliness 68/100

mdn/browser-compat-data#29572 · 3 comments · Opened Apr 29, 2026
Popover - Safari breaks browser convention in how it translates popover components to screen-readers Open

acd browser:safari

Difficulty 3/5 1-2 days Newbie friendliness 52/100

mdn/browser-compat-data#29566 · 6 comments · Opened Apr 29, 2026
css.at-rules.supports.at-rule - missing compat data for @supports at-rule() Open

browser:multiple data:css info needed

Difficulty 2/5 1-3 hours Newbie friendliness 76/100

mdn/browser-compat-data#29549 · 2 comments · Opened Apr 27, 2026
css.selectors.current - Missing compatibility data Open

data:css p3

mdn/browser-compat-data#29543 · 3 comments · 1 assignee · Opened Apr 26, 2026
Extend description linter for static API members Open

infra

Difficulty 2/5 1-3 hours Newbie friendliness 75/100

mdn/browser-compat-data#29537 · Opened Apr 24, 2026
api.Window.load_event - is not working as expected in the latest ios safari Open

browser:safari_ios data:api info needed

Difficulty 2/5 1-3 hours Newbie friendliness 48/100

mdn/browser-compat-data#29527 · 1 comment · Opened Apr 22, 2026
Firefox release "retired" before new release is "current" Open

infra

Difficulty 3/5 1-2 days Newbie friendliness 48/100

mdn/browser-compat-data#29522 · Opened Apr 22, 2026
api.DeviceOrientationEvent is deprecated on Firefox, but this isn't mentioned on the page Open

browser:firefox data:api p3

Difficulty 2/5 1-3 hours Newbie friendliness 62/100

mdn/browser-compat-data#29409 · 6 comments · Opened Apr 6, 2026
api.Element.animationcancel_event - chromium supports `onanimationcancel` property Open

blocked browser:chrome data:api needs collector update p2

Difficulty 2/5 1-3 hours Newbie friendliness 68/100

mdn/browser-compat-data#29376 · 7 comments · Opened Mar 31, 2026
api.PerformanceObserver.observe - Missing options data Open

browser:multiple data:api meeting agenda needs collector test p3

Difficulty 4/5 3-5 days Newbie friendliness 48/100

mdn/browser-compat-data#29426 · 7 comments · Opened Mar 31, 2026
html.elements.meta.name.color-scheme - Not working in Samsung Internet Browser Open

browser:samsunginternet_android data:html meeting agenda

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mdn/browser-compat-data#29347 · 4 comments · Opened Mar 26, 2026
css.at-rules.counter-style.symbols - add subfeatures for specific `<symbol>` values? Open

browser:multiple data:css needs collector test p3

Difficulty 3/5 1-2 days Newbie friendliness 55/100

mdn/browser-compat-data#29344 · Opened Mar 25, 2026
Authoring pains workshop Open

meeting agenda

Difficulty 5/5 Over a week Newbie friendliness 25/100

mdn/browser-compat-data#29326 · 1 comment · Opened Mar 24, 2026
Description guidelines Open

docs:guidelines

Difficulty 3/5 1-2 days Newbie friendliness 45/100

mdn/browser-compat-data#29316 · Opened Mar 23, 2026

mdn/browser-compat-data

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