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 first139 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. 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/CADNavw6ik9WQ5AMqY4TzKr_DssT1ko11x5Ruiar%3D-ssf9LytZA%40mail.gmail.com.
