Hi Alex, I've added a statement from Unity to the "Web / Framework developer views notes". Unity is an important partner, so this carries some weight. We will add more if/when it comes in.
Stephen On Wed, Jan 14, 2026 at 11:05 AM Alex Russell <[email protected]> wrote: > It's a little odd that there's no developer feedback here. Is it correct > that we're shipping first? And is there a list of features that will not be > available in this mode? Does it unlock software rendering? > > Thanks, > > Alex > > On Wednesday, January 14, 2026 at 6:22:11 AM UTC-8 Stephen White wrote: > >> Sure! The above proposal was converted into spec text on a feature >> branch. This >> <https://github.com/gpuweb/gpuweb/commit/6eae31ebb74b4877d91ddce47865ba89bf1ae1a5> >> is >> the merge commit that brought those changes into the main spec. The changes >> are not isolated to a single section, but each restriction appears in a >> cyan box labelled "Compatibility Mode", easiest to find by searching for >> "core-features-and-limits". >> >> These are the (largely minor) followup changes that landed after that >> merge: >> >> - Disallow cube-array in createTexture >> >> <https://github.com/gpuweb/gpuweb/commit/f34e4301de148b82936737bf7312c0a496b6e7e2> >> - Fix maxStorageTexturesIn*Stage defaults >> >> <https://github.com/gpuweb/gpuweb/commit/78dfad2eb1c8dcbd00430562e147eb3a052a5e3e> >> - [editorial] Tweak requestAdapter step ordering, feature level >> definitions (again) >> >> <https://github.com/gpuweb/gpuweb/commit/b984d18e327a5691dfdf7cc2b8746972552e2c54> >> >> Stephen >> >> On Wed, Jan 14, 2026 at 8:48 AM Yoav Weiss (@Shopify) < >> [email protected]> wrote: >> >>> >>> >>> On Tuesday, January 13, 2026 at 9:16:24 PM UTC+1 Chromestatus wrote: >>> >>> *Contact emails* >>> [email protected], [email protected] >>> >>> *Explainer* >>> https://github.com/explainers-by-googlers/webgpu- >>> compatibility-mode/blob/main/README.md >>> >>> *Specification* >>> https://github.com/gpuweb/gpuweb/blob/main/proposals/ >>> compatibility-mode.md >>> >>> >>> Can you point to a PR or a spec section that includes the change? >>> >>> >>> >>> >>> *Summary* >>> Adds an opt-in, lightly restricted subset of the WebGPU API capable of >>> running older graphics APIs such as OpenGL and Direct3D11. By opting into >>> this mode and obeying its constraints, developers can extend the reach of >>> their WebGPU applications to many older devices that do not have the >>> modern, explicit graphics APIs that core WebGPU requires. For simple >>> applications, the only required change is to specify the "compatibility" >>> featureLevel when calling requestAdapter. For more advanced applications, >>> some modifications may be necessary to accommodate the mode's restrictions. >>> Since Compatibility mode is a subset, the resulting applications are also >>> valid WebGPU Core applications and will run even on user agents that do not >>> support Compatibility mode. >>> >>> *Blink component* >>> Blink>WebGPU >>> <https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EWebGPU%22> >>> >>> *Web Feature ID* >>> webgpu <https://webstatus.dev/features/webgpu> >>> >>> *Motivation* >>> WebGPU is a good match for modern graphics APIs such as Vulkan, Metal >>> and Direct3D 12. However, there are a large number of devices which do not >>> yet support those APIs. In particular, on Chrome on Windows, 31% of Chrome >>> users do not have Direct3D FL 11.1 or higher. On Android, 23% of Android >>> users do not have Vulkan 1.1, including 15% who do not have Vulkan at all ( >>> https://developer.android.com/about/dashboards). On ChromeOS, Vulkan >>> penetration is still quite low, while OpenGL ES 3.1 is ubiquitous. >>> Developers are thus forced to write multiple implementations (e.g., WebGPU >>> and WebGL) for maximum reach, to accept the reduced reach that core WebGPU >>> currently provides, or to write only for WebGL and forgo the advanced >>> features of WebGPU, such as GPU compute. By opting in to Compatibility >>> Mode, developers can target a wider reach of devices with a single >>> implementation. >>> >>> *Initial public proposal* >>> https://github.com/gpuweb/gpuweb/blob/main/proposals/ >>> compatibility-mode.md >>> >>> *TAG review* >>> https://github.com/w3ctag/design-reviews/issues/1063 >>> >>> *TAG review status* >>> Issues addressed >>> >>> *Origin Trial Name* >>> WebGPU Compatibility Mode >>> >>> *Chromium Trial Name* >>> WebGPUCompatibilityMode >>> >>> *Origin Trial documentation link* >>> https://github.com/explainers-by-googlers/webgpu- >>> compatibility-mode/blob/main/README.md >>> >>> *WebFeature UseCounter name* >>> kWebGPUFeatureLevelCompatibility >>> >>> *Risks* >>> >>> >>> *Interoperability and Compatibility* >>> This feature has been approved in W3C GPU for the Web WG meetings >>> including participants from Safari and Firefox. >>> >>> *Gecko*: Positive Although there is not currently an entry for >>> Compatibility Mode in the standards positions repos, WebGPU Compatibility >>> Mode was discussed and approved by Google, Apple and Mozilla in the GPU for >>> the Web Working Group, and has the same support as WebGPU Core. Each of the >>> commits to the compatibility-mode propsal above was approved by a working >>> group member from each of those three organizations, and any disagreements >>> were resolved prior to landing in Working Group meetings. >>> >>> *WebKit*: Positive Although there is not currently an entry for >>> Compatibility Mode in the standards positions repos, WebGPU Compatibility >>> Mode was discussed and approved by Google, Apple and Mozilla in the GPU for >>> the Web Working Group, and has the same support as WebGPU Core. Each of the >>> commits to the compatibility-mode propsal above was approved by a working >>> group member from each of those three organizations, and any disagreements >>> were resolved prior to landing in Working Group meetings. >>> >>> *Web developers*: No signals >>> >>> *Other signals*: >>> >>> *Security* >>> Being a lightly-restricted subset, Compatibility Mode does not introduce >>> any accessibility, security, or privacy issues over and above those >>> introduced by core WebGPU. For this reason, the security review submitted >>> for WebGPU also applies to Compatibility Mode. >>> >>> *WebView application risks* >>> >>> Does this intent deprecate or change behavior of existing APIs, such >>> that it has potentially high risk for Android WebView-based applications? >>> Low; does not remove or alter existing APIs. Provides a >>> lightly-restricted subset of the WebGPU API to older devices which are not >>> capable of the core WebGPU API In case of emergency, there are two >>> independent killswitches: - kWebGPUAndroidOpenGLES controls the Dawn >>> OpenGLES backend on Android in the GPU process - RuntimeEnabledFeature >>> kWebGPUCompatibilityMode controls the JS API in the renderer process >>> >>> >>> *Debuggability* >>> *No information provided* >>> >>> *Will this feature be supported on all six Blink platforms (Windows, >>> Mac, Linux, ChromeOS, Android, and Android WebView)?* >>> No >>> All platforms will eventually have support. Will immediately be >>> available on Android, Android WebView, ChromeOS, Mac, and Windows, where >>> hardware support is available. Linux is planned to have WebGPU support in >>> the future, so this feature will become available when WebGPU does. >>> >>> *Is this feature fully tested by web-platform-tests >>> <https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?* >>> Yes >>> All Compatibility Mode restrictions are exercised by the "compatibility" >>> option to the WebGPU CTS. E.g., https://gpuweb.github.io/cts/ >>> standalone/?compatibility=1&q=webgpu:* This subset is tested >>> extensively on the Dawn CI (https://ci.chromium.org/p/ >>> chromium/g/chromium.dawn/console) under the "webgpu_cts_compat_tests" >>> suite. WebGPU/WGSL have a conformance test suite ( >>> https://github.com/gpuweb/cts) that is regularly pulled into Chromium >>> and part of the testing of Dawn/Tint in Chromium. While the CTS can be >>> embedded in WPT, the WebGPU team opted to keep it separate in Chromium >>> testing to use a customized harness for robustness and performance. >>> >>> *Flag name on about://flags* >>> *No information provided* >>> >>> *Finch feature name* >>> WebGPUCompatibilityMode >>> >>> *Rollout plan* >>> Will ship enabled for all users >>> >>> *Requires code in //chrome?* >>> False >>> >>> *Tracking bug* >>> https://crbug.com/442618060 >>> >>> *Availability expectation* >>> Mozilla is interested in this feature (and has approved all of the spec >>> changes) but has not committed to implementing it yet. Apple has approved >>> all of the spec changes, but it is not anticipated that this feature will >>> ship in Safari since all Apple devices on the market can support the full >>> Core WebGPU spec. However, since it is designed as a subset, Compatibility >>> mode applications will work unchanged in browsers that only support Core >>> (e.g., Safari). >>> >>> *Adoption expectation* >>> Feature is used by specific partner(s) to provide functionality within >>> 12 months of launch in Chrome. >>> >>> *Adoption plan* >>> Adoption of Core WebGPU proceeds apace (https://chromestatus.com/ >>> metrics/feature/timeline/popularity/4029), and it is expected that >>> developers will adopt Compatibility Mode because it allows them to extend >>> the reach of their WebGPU content to a larger audience. >>> >>> *Non-OSS dependencies* >>> >>> Does the feature depend on any code or APIs outside the Chromium open >>> source repository and its open-source dependencies to function? >>> On Android, this feature depends on the OpenGLES 3.1 graphics API in >>> order to provide WebGPU capability to older devices. The JavaScript API >>> will be available on all platforms, including desktop, but will not require >>> any new graphics APIs; it will simply allow developers to test the >>> Compatibility Mode subset on all Chrome platforms. >>> >>> *Estimated milestones* >>> Shipping on desktop146 Origin trial desktop first139 Origin trial >>> desktop last145 Shipping on Android146 Origin trial Android first139 Origin >>> trial Android last145 Shipping on WebView146 Origin trial WebView first >>> 139 Origin trial WebView last145 >>> >>> *Anticipated spec changes* >>> >>> Open questions about a feature may be a source of future web compat or >>> interop issues. Please list open issues (e.g. links to known github issues >>> in the project for the feature specification) whose resolution may >>> introduce web compat/interop risk (e.g., changing to naming or structure of >>> the API in a non-backward-compatible way). >>> All Compatibility Mode changes have landed in the WebGPU core spec: >>> https://www.w3.org/TR/webgpu/; all known issues have been addressed. >>> >>> *Link to entry on the Chrome Platform Status* >>> https://chromestatus.com/feature/6436406437871616?gate=6221450639572992 >>> >>> *Links to previous Intent discussions* >>> Intent to Experiment: https://groups.google.com/a/ >>> chromium.org/d/msgid/blink-dev/683618d7.170a0220.2aa17e. >>> 17c5.GAE%40google.com >>> >>> >>> This intent message was generated by Chrome Platform Status >>> <https://chromestatus.com>. >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "blink-dev" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To view this discussion visit >>> https://groups.google.com/a/chromium.org/d/msgid/blink-dev/2c05e366-fc6b-453d-a4a6-86f3c38076f9n%40chromium.org >>> <https://groups.google.com/a/chromium.org/d/msgid/blink-dev/2c05e366-fc6b-453d-a4a6-86f3c38076f9n%40chromium.org?utm_medium=email&utm_source=footer> >>> . >>> >> -- You received this message because you are subscribed to the Google Groups "blink-dev" group. 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