How the WebGL test works
The page asks your browser for a WebGL 2 context, then a WebGL 1 context if that fails, and draws a shaded cube with it. It then reads the pixel in the middle of the image back from the GPU. A cube you can see and a lit pixel mean the whole pipeline works: shaders compiled, geometry drawn and the result delivered. That is a stronger check than testing whether the WebGL object exists, which some sites stop at.
The result at the top reads:
- WebGL 2 works: both versions are available and the render test passed.
- Only WebGL 1 works: WebGL 2 is missing, so newer 3D sites and games may refuse to start. An old graphics driver or a blocklisted GPU is the usual cause.
- WebGL works, without your GPU: rendering falls back to a software renderer, so it is slow. The acceleration steps below fix most cases.
- WebGL is off or blocked: no context at all.
Reading the WebGL report
The panel under the table lists the version strings, the limits your GPU and browser allow (largest texture, renderbuffer and viewport, anti-aliasing samples, texture units, uniform vectors, anisotropic filtering) and every extension, sorted by name. The renderer string above it names the graphics API WebGL is translated to. Developers can copy the whole summary with Copy details to paste into a bug report.
If a site says WebGL is not supported but this test passes, the site may need an extension your browser doesn’t list, or it may be checking the browser name rather than testing WebGL. Try the site in another browser to compare.