Blink-only Web APIs present for a Chrome UA
Check id blink-web-apis
What an ordinary browser yields
All four Blink-only surfaces present on a secure page with a desktop Chrome UA — or N/A on Brave (stock fingerprinting defences remove some), on insecure origins, or on a non-Chrome UA.
What a detector infers
When the UA matches `Chrome/\d+` and the page is a secure context, this probes four Blink-only surfaces: `navigator.connection`, `navigator.userAgentData`, `performance.memory`, and — unless the UA is an iOS wrapper or mobile, where it is legitimately absent — `navigator.keyboard`. `navigator.userAgentData` is genuinely Blink-only — no Gecko or WebKit release ships it — while `navigator.connection` is absent from WebKit and from desktop Gecko (Firefox exposes NetworkInformation only on Android), and performance.memory is a non-standard Chromium-only API. Against a desktop Chrome UA, then, their absence is a direct statement about which engine is executing the JS, independent of what the UA string says. A detector reading a Chrome UA with no userAgentData learns that the UA is a costume over a different engine (Camoufox and similar desktop-Firefox-based tools land here). Two deliberate carve-outs keep the check honest. The secure-context gate matters because userAgentData is only exposed over HTTPS, so the check goes N/A on insecure origins or a non-Chrome UA rather than producing a false failure. And Brave is declined outright: it strips or neutralises some of these surfaces as stock fingerprinting defences (the corpus showed 100% of genuine Brave failing), which is a privacy feature, not an engine lie — the same exemption pattern as canvas-tamper.
How to resolve it
Align the UA with the engine actually running. If you need a Chrome identity, run a Chromium-based browser; a Gecko engine cannot grow these APIs, and shimming them in JS leaves other Blink-surface checks (CSS registry, masked WebGL vendor, productSub) still contradicting.
Read in the wild by
PerimeterX / HUMAN
Records the bare existence of navigator.userAgentData as a boolean, and probes navigator.connection / mozConnection / webkitConnection — reporting a `support` boolean alongside an enumeration of the object's live values (effectiveType, rtt, downlink, saveData). Separately hashes a hasOwnProperty census over a window API list containing both Gecko-only (mozInnerScreenX, mozRTCPeerConnection, Dump) and WebKit-only (webkitMediaStream, webkitRTCPeerConnection, webkitSpeechGrammarList) names, with sibling censuses over document and location.
Deployed iFood PX collector, stample/ifood/source/main.min.js. Aliases assigned once each in-file: `hS=window`, `hT=document`, `hU=navigator`, `hV=location`; hQ() indices per bug_report/sdk_drift_cases/2026-05-19_ifood/hQ_map.json; line numbers per all_fields_map.json (js-beautify'd). userAgentData — literal: `t[0]["Q3M2OQYTMAM="]=!!hU.userAgentData` (line 8083) → EV2 "Q3M2OQYTMAM=" = true. connection — `function xw(t){try{var n,e=hU,r=e[hQ(369)]||e[hQ(370)]||e.webkitConnection,h={};for(var i in r)r[hQ(274)][hQ(145)](i)&&null!==r[i]&&(h[i]=r[i]);t[hQ(371)]=((n={})[hQ(372)]=!!r,n.status=h,n)}catch(t){}}` with hQ(369)='connection', hQ(370)='mozConnection', hQ(372)='support' → EV2 "eWVMLzwFSRQ=" = {"support":true,"status":{"effectiveType":"3g","rtt":350,"downlink":1.35,"saveData":false}} (stample/ifood/sample/5/decoded_payload_2.json). window census — `t["STU8fw9UO08="]=AW(hS,o)` (line 7133) → "7c5f9724". AW accumulates `""+hM[0].hasOwnProperty(hM[1][i])` across the list and returns kn(...), a 32-bit rolling hash. o=["closed",hQ(519)='devicePixelRatio',hQ(520)='getSelection',"locationbar","scrollbars",hQ(521)='crypto',"caches","speechSynthesis",hQ(522)='menubar',"personalbar","toolbar","Dump",…,"VRDisplayCapabilities",…,hQ(524)='mozInnerScreenX',"mozInnerScreenY","mozRTCIceCandidate","mozRTCPeerConnection","mozRTCSessionDescription",hQ(525)='webkitMediaStream',hQ(526)='webkitRTCPeerConnection',"webkitSpeechGrammar",hQ(527)='webkitSpeechGrammarList',…]. Siblings: AW(hT,c) → "EX1kN1QaZw0=" (line 7135), AW(hV,u) → "XGhpYhoKY1A=" (line 7139). Source: github.com/warterbili/PerimeterX_RE (public).
Every attribution traces to a published artifact. See the sources and their limits.
Nearby checks in Environment & locale
- 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… - 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… - navigator.plugins is a real platform object (structured-clone probe)
plugins-structured-cloneThe structured-clone algorithm is implemented in C++ and interrogates objects about what they actually are, not what they claim. - canPlayType answers identically for <video>, <audio> and the prototype
canplaytype-element-agnosticcanPlayType is implemented exactly once, on HTMLMediaElement.prototype, so <video> and <audio> inherit the same C++ function.
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 blink-web-apis belongs to.