WebGL renderer (software vs hardware)
Check id webgl-not-software
What an ordinary browser yields
A hardware renderer string. The check marks SwiftShader / llvmpipe / "Software" as a tell, but at info severity it is excluded from the score — and CPU rasterisation is legitimate on VDI/RDP, with hardware acceleration off, on blocklisted GPUs and on driverless Linux.
What a detector infers
The audit reads UNMASKED_RENDERER through the WEBGL_debug_renderer_info extension and matches it against SwiftShader, llvmpipe and Software. Those names mean the page is being rasterised on the CPU rather than a GPU, which is the default in many headless and container setups — but equally in VDI/RDP sessions, with hardware acceleration switched off, on blocklisted GPUs, and on driverless Linux. Because CPU rasterisation is a perfectly legitimate state on its own, this check is info severity and is excluded from the score entirely. What makes a renderer string evidence is not its value but its agreement with other surfaces — a detector infers far more from a software renderer that contradicts a discrete-GPU string reported elsewhere than from a software renderer alone.
How to resolve it
Nothing to fix if the software renderer is real; it is a coherent state that many ordinary users report, and this check does not affect the score. Only act if it contradicts a GPU claimed on another surface — then make the two agree, either by giving the browser a real GPU-backed render path (canvas bridge) or by dropping the discrete-GPU string.
Read in the wild by
Kasada
It collects the unmasked WebGL renderer string and its script embeds a full SwiftShader ANGLE renderer string as a literal to compare against.
Decompiled ips.js compares the collected renderer against a hardcoded software-renderer string — 2.txt:32222: r4 = _5784["gpv"]; r5 = r4 === "ANGLE (Google, Vulkan 1.3.0 (SwiftShader Device (Subzero) (0x0000C0DE)), SwiftShader driver)". The gpv value comes from func_01dfb7 (2.txt:31508), which calls getExtension("WEBGL_debug_renderer_info") then getParameter(UNMASKED_RENDERER_WEBGL). The literal is also in the ips.js __strTable at 2.txt:1. Corroborating probe labels from the teardown's 427/427 mapped probe list: gl_unmasked_renderer, webgl1_unmasked_renderer, webgl2_unmasked_renderer.
PerimeterX / HUMAN
Pulls UNMASKED_RENDERER_WEBGL and UNMASKED_VENDOR_WEBGL through the WEBGL_debug_renderer_info extension and ships each as its own field.
PerimeterX collector `stample/ifood/source/main.min.js`: `var r=t[hQ(491)]("WEBGL_debug_renderer_info");r&&(n.unmaskedVendor=Ak(t,r.UNMASKED_VENDOR_WEBGL),n[hQ(492)]=Ak(t,r.UNMASKED_RENDERER_WEBGL))`, where the string table resolves hQ(491)='getExtension' and hQ(492)='unmaskedRenderer'. Both are emitted as their own payload fields — `e["Y1NWWSY1UWk="]=n.unmaskedVendor,e["GwtuAV1qaTY="]=n.unmaskedRenderer` — and those keys carry "Google Inc. (Intel)" and "ANGLE (Intel...)" in captured payloads (`stample/ifood/sample/1/decoded_payload_2.json`). The same collection appears in `stample/grub/source/init.js`.
CreepJS
CreepJS, a research demo rather than a production detector, regex-matches SwiftShader in the worker-scope WebGL renderer string and counts it toward its "like headless" rating.
src/headless/index.ts:89 (abrahamjuliot/creepjs, master): `hasSwiftShader: /SwiftShader/.test(workerScope?.webglRenderer),` — a key of the `likeHeadless` object, enumerated at line 162 (`Object.keys(likeHeadless)`) and scored at line 166 (`likeHeadlessRating = +((likeHeadlessKeys.filter((key) => likeHeadless[key]).length / likeHeadlessKeys.length) * 100).toFixed(0)`), rendered at line 253 as `${likeHeadlessRating}% like headless`.
Every attribution traces to a published artifact. See the sources and their limits.
Nearby checks in Render & GPU
- WebGPU vendor coheres with WebGL vendor
webgl-webgpu-vendorTwo independent graphics stacks in the same browser are backed by the same physical adapter: this check lowercases the WebGL UNMASKED_VENDOR… - WebGL exposes a full parameter table + UNMASKED vendor/renderer
webgl-param-tableBeyond the two headline strings, a WebGL context answers getParameter for dozens of driver-specific limits. - WebGL vendor/renderer identical in a Worker
webgl-worker-vs-mainThe audit reads UNMASKED_VENDOR and UNMASKED_RENDERER on the main thread, then spawns a dedicated Worker that builds its own WebGL context… - 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. - one pixel reads the same through a full read and a windowed read
canvas-subrect-consistencyThe same pixels, asked for twice through different windows. A full-canvas read and an inner 16×16 read overlap on 256 pixels, and those are…
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-not-software belongs to.