Browser clock and the IP's timezone, resolved at the same instant
Check id ip-tz-offset-delta
What an ordinary browser yields
Contextual only: your clock's offset and the offset of your IP's timezone agree at the same instant, or differ by an amount travel and DST explain.
What a detector infers
This is the only check here whose two sides are observed by different parties. The browser reports its own UTC offset; the edge reports the IANA timezone it derived from the address the connection arrived on. Both are then resolved AT THE SAME INSTANT — the IP's zone offset is computed for the current moment via Intl rather than read from a stored table, which is what makes the comparison survive daylight saving. (Comparing against a stored offset produces a bug that passes every test written in July and fires in October, and because the hemispheres transition in different windows it fires for different readers at different times of year.) The mechanism a detector relies on is that these two facts have separate causes: your clock is a setting on your machine, while your IP is a consequence of the route your packets took. A proxy or VPN relocates the second and cannot touch the first, so the pair drifts apart. This is graded rather than binary and is never a verdict: it is reported as a delta, because the honest reading of a mismatch is "these two are configured differently", not "this person is lying".
How to resolve it
If you are presenting a location, make the machine's timezone match the exit IP's region — the clock is the half you control. A mismatch is genuinely ordinary for VPN users, travellers, expats and developers who run their machines in UTC, which is exactly why this row is contextual, contributes nothing to the score, and never renders as a failure.
Other checks in Connection & locale
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 Connection & 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 Connection & locale — the family ip-tz-offset-delta belongs to.