WebGL vendor/renderer identical in a Worker
Worker and main thread name the identical vendor and identical renderer.
What a detector infers
The audit reads UNMASKED_VENDOR and UNMASKED_RENDERER on the main thread, then spawns a dedicated Worker that builds its own WebGL context on an OffscreenCanvas and reads the same two strings, requiring exact equality of both. A Worker is a separate JavaScript realm with its own globals: a patch applied to the page's WebGLRenderingContext.prototype.getParameter never executes there, so the Worker reports the real GPU while the main thread reports the fictional one.
A detector treats that as a high-confidence signal because no physical machine presents two different GPUs to two scopes of the same page — the disagreement can only come from a modification that covers one scope. N/A if the Worker probe errors or times out (4s), or if either scope has no debug-renderer-info to read.
How to resolve it
Move GPU identity below JavaScript — an engine-level control or a canvas bridge — so every realm reads the same value from one source of truth. Chasing this by also injecting into every Worker is fragile: each new realm (Workers, nested Workers, iframes) is another place the patch must reach.
Read in the wild by
CreepJS
CreepJS, an open-source fingerprinting research demo rather than a production detector, compares the main-thread UNMASKED_RENDERER_WEBGL string against the renderer a worker scope reports and flags any inequality as `hasBadWebGL`, one of the booleans in its `stealth` group that feed its stealth rating.
src/headless/index.ts — `hasBadWebGL: (() => { const { UNMASKED_RENDERER_WEBGL: gpu } = webgl?.parameters || {}; const { webglRenderer: workerGPU } = workerScope || {}; return (gpu && workerGPU && (gpu !== workerGPU)) })(),` — declared inside the `stealth` group of `getHeadlessFeatures`, which is scored as `(stealthKeys.filter((key) => stealth[key]).length / stealthKeys.length) * 100`.
Every attribution traces to a published artifact. See the sources and their limits.
Nearby checks in Render & GPU
- WebGL parameters return the JavaScript types the specification assigns them
webgl-param-value-typesgetParameter does not return loose values: the WebGL specification fixes the JavaScript TYPE of each one. - The anisotropy limit reads as a number once its WebGL extension is enabled
webgl-anisotropy-after-extensionEXT_texture_filter_anisotropic adds exactly one parameter to getParameter, MAX_TEXTURE_MAX_ANISOTROPY_EXT, and the extension guarantees it… - A Direct3D 11 WebGL renderer reports the uniform limits ANGLE fixes for its vendor
webgl-d3d11-limits-vs-vendorChrome, Edge, Brave and Firefox on Windows render WebGL through ANGLE's Direct3D 11 backend, and that backend does not ask the driver for… - A Mesa OpenGL WebGL renderer reports the varying and uniform limits Mesa and ANGLE give it
webgl-mesa-limits-vs-driverChrome on Linux renders WebGL through ANGLE's OpenGL backend, which does not invent shader limits: it reads MAX_VARYING_VECTORS from the GL… - Masked WebGL VENDOR matches the engine
webgl-engine-vendorThis check reads the plain gl.getParameter(gl.VENDOR) — the masked value, not the debug extension's unmasked GPU string. - WebGL1 and WebGL2 report the same UNMASKED GPU
webgl1-webgl2-coherenceThe check creates a WebGL1 context and a WebGL2 context and reads UNMASKED_VENDOR_WEBGL / UNMASKED_RENDERER_WEBGL from each through the… - Canvas readback is not noise-injected (1×1 probe)
canvas-tamperThe probe fills a single pixel with pure black on a 1x1 canvas and reads it straight back with getImageData. - One flat fill reads back as exactly one colour
canvas-flat-fill-uniformThis is the area form of the 1×1 canvas probe, and it exists because that probe is easy to pass by accident.
Clearcote is a browser built for fingerprint coherence
It is a Chromium fork, maintained by the same people who wrote this reference. It ships as a compiled browser rather than as a stealth script injected into someone else's — which is a description of how it is built, and is not an argument about how it behaves on this check.
This audit takes no position on how Clearcote scores on Render & GPU checks, on this one, or anywhere else. It has no baseline corpus of other people's fingerprints to rank you against and no vendor scoreboard — nearly every check is self-referential, asking one browser the same question through two independent APIs and reporting whether both answers can be true at once. It runs identically on any browser, including ours. Run it on yours and read the result yourself.
See the other checks in Render & GPU — the family webgl-worker-vs-main belongs to.