navigator.connection.downlink sits on Chrome's 50 kbps grid, capped at 10
downlink is a multiple of 0.05 and at most 10. N/A without the Network Information API and on non-Chromium engines (severity: warn).
What a detector infers
navigator.connection.downlink is not a raw measurement. Blink's NetworkStateNotifier multiplies the network-quality estimate by a per-host factor between 0.90 and 1.10, caps the result at 10 Mbps and rounds it to the nearest 50 kbps, so every value a page can see is a multiple of 0.05 and no larger than 10 (kBucketSize and kMaxDownlinkKbps in network_state_notifier.cc).
A free-form number chosen to look realistic, such as 7.37, lands off the grid, and anything above 10 is above the cap. In the audit's corpus, every Blink capture but one sits on the grid; the exception, a visitor claiming Chrome 150, reported a downlink of 60.
Every arm measured here read between 1.45 and 10, all on the grid, and DevTools' throttling presets land on it too, so throttling is not a false positive. connection-rtt-quantization checks the round-trip estimate; this row checks the bandwidth estimate that travels beside it. N/A where navigator.connection or its downlink is absent, as in Firefox and Safari.
How to resolve it
Leave the Network Information API to the browser. A value that is set by hand has to be one Chromium can produce — a multiple of 0.05 Mbps, at most 10 — and a realistic-looking decimal usually is not.
Nearby checks in Network & WebRTC
- 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. - Canvas text is anti-aliased the way the claimed OS rasterises it
glyph-aa-levels-vs-osCanvas text is rasterised by the platform's font engine, and the engines leave different fingerprints in the alpha channel. - 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 downlink-on-50kbps-grid belongs to.