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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