an enabled PDF viewer exposes exactly the specified plugin set
With the PDF viewer enabled: exactly five plugins and two mime types. With it disabled: empty lists, which this row does not judge.
What a detector infers
A deployed commercial agent devotes four separate signals to this one small area: the plugin count, a plugin presence bit, the mime-type count, and a mime-type presence bit. Four wire slots for what looks like a single fact is a strong hint that the numbers themselves are what it wants.
And they are worth wanting, because these lists stopped being discovered and became legislated: the specification fixes a hardcoded PDF-viewer plugin set and the mime types that go with it, precisely so the surface would stop carrying entropy. A browser with the viewer enabled therefore exposes exactly that many entries and no others, which makes this one of the very few places where three different engines are obliged to agree on a NUMBER rather than merely on a shape.
The captures shipped with the teardown bear that out — Chrome, Firefox and Safari on one machine all reporting the viewer enabled, five plugins, two mime types. Three independent engines, identical values.
What this adds to its neighbours is cardinality and nothing else, which is exactly the gap they leave: the plugin-presence row asserts only that an enabled viewer implies a non-empty list, and the structural row asserts that the arrays are genuine platform objects whose mime types map back onto plugins that are really present. A build exposing three plugins, or eight, satisfies both of those completely.
Only the enabled branch is scored, because with the viewer switched off the lists are legitimately empty on mobile, on iOS and under enterprise policy, and the neighbouring row already adjudicates that case.
How to resolve it
If the plugin list is synthesised, reproduce the specified set exactly rather than approximating it. The counts were standardised to remove the entropy, so any other number puts the build in a population of its own — and because length is read separately from structure, a list that is internally consistent still fails on its size.
Nearby checks in Environment & locale
- IANA zone offset matches the JS clock offset (incl. across DST)
timezone-offset-coherenceThis is a two-source cross-check on the same fact. It takes the resolved IANA zone, formats the current instant through Intl.DateTimeFormat… - navigator.plugins is consistent with the PDF viewer
has-pluginsAn empty navigator.plugins is only meaningful when it contradicts something else, and this check is written to respect that. - navigator.pdfViewerEnabled is true
pdf-viewerA direct read of navigator.pdfViewerEnabled. It is N/A when the property is not exposed at all, passes when true, and is marked false… - mimeTypes are consistent with navigator.plugins
plugins-mimetypesThis walks navigator.mimeTypes, and for each entry reads .enabledPlugin and checks that the exact object is present in a Set built from… - proprietary codecs (H.264 / AAC) present for a Chrome UA
codec-supportThe check calls canPlayType on a video and audio element for H.264 ('avc1.42E01E') and AAC ('mp4a.40.2'), plus MP4/WebM/Ogg for context, and… - Blink-only Web APIs present for a Chrome UA
blink-web-apisWhen the UA matches Chrome/\d+ and the page is a secure context, this probes four Blink-only surfaces: navigator.connection… - CSS feature support matches the engine (Blink for a Chrome UA)
css-engine-surfaceFor any UA containing 'Chrome/', this requires CSS.supports('-webkit-app-region', 'drag') to be true and the Gecko markers — MozAppearance… - every Intl constructor resolves the same locale
intl-locale-coherenceEvery Intl constructor — NumberFormat, DateTimeFormat, PluralRules, Collator — resolves its locale through the same underlying ICU data, so…
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 Environment & locale 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 Environment & locale — the family pdf-plugin-set-cardinality belongs to.