Canvas text is anti-aliased the way the claimed OS rasterises it
Under a Windows claim, canvas text shows at most 24 distinct partial-alpha levels (about 15 is typical). N/A under other claims and on non-Chromium engines (severity: warn).
What a detector infers
Canvas text is rasterised by the platform's font engine, and the engines leave different fingerprints in the alpha channel. On Windows, Chrome takes glyph coverage from DirectWrite, and the anti-aliased edges of canvas text come out in a small number of coarse steps: black 16 px Arial drawn on a transparent canvas shows 15 distinct partial-alpha levels on Chrome and Edge.
On Linux, FreeType produces nearly continuous coverage: 238 distinct levels for the same text, headed or headless. The row counts distinct alpha values between 1 and 254 and, under a Windows claim, expects no more than 24. Counting levels rather than matching exact values is deliberate — ClearType tuning shifts which levels appear, but not how many by an order of magnitude. Genuine Linux Chrome claiming Windows kept its 238 levels. Two limits are stated rather than hidden.
The Windows figure was measured with ClearType on, and a machine with font smoothing off, common over Remote Desktop, has not been measured yet. And the rule describes Chromium's text path, so other engines are not judged by it. Unlike the text-metric rows, which read glyph advances and boxes, this one reads the rasteriser itself.
How to resolve it
Anti-aliasing comes from the host's font rasteriser, which a user-agent override does not touch. Present the OS the browser actually renders text on.
Nearby checks in Network & WebRTC
- navigator.connection.downlink sits on Chrome's 50 kbps grid, capped at 10
downlink-on-50kbps-gridnavigator.connection.downlink is not a raw measurement. Blink's NetworkStateNotifier multiplies the network-quality estimate by a per-host… - A server-reflexive candidate only appears when a STUN server answered
srflx-only-from-answering-stunA server-reflexive (srflx) ICE candidate is the public address a STUN server reports back in its reply to a binding request. - Every server-reflexive address is one the STUN server actually handed out
srflx-was-seen-by-stunA server-reflexive candidate exists only after a STUN server received a binding request from that public address and replied with it. - Emoji come from the claimed OS's emoji font
emoji-font-vs-osEmoji are drawn from the operating system's colour emoji font, and the fonts differ in a way measureText can see without rendering a pixel. - The default monospace font is the claimed OS's
monospace-default-vs-osThe generic monospace family resolves to a font the platform chooses. - The JS heap ceiling fits the memory the browser reports
heap-ceiling-vs-device-memorynavigator.deviceMemory and V8's heap ceiling, performance.memory.jsHeapSizeLimit, look unrelated but are computed from the same number: the… - The address WebRTC exits from matches the address this page was served to
webrtc-ip-vs-connectionThis is the one check on this page that cannot be answered from inside the page, and the only one that makes a network call. - Relay-forced WebRTC exits the same address this page arrived from
webrtc-turn-egressEvery other WebRTC check on this page reads what the browser is willing to show it.
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 Network & WebRTC 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 Network & WebRTC — the family glyph-aa-levels-vs-os belongs to.