Timezone and IP consistency checker
Half of what a consistency scanner reads is whether your IP’s location agrees with your browser clock and language. This checks exactly that: your timezone, offset, locale and Accept-Language against the country and timezone of your IP, and says in plain words whether a site would see one place or two.
Your browser values are read here; your IP’s location comes from your own request to our server.
Why four lines. One mismatch can be innocent — people travel, expats keep a home language. Several at once is the pattern a scanner reads as a mask. The Accept-Language versus navigator.languages line is the strictest: no normal browser disagrees with itself there.
The signal, line by line
A site can read your timezone and languages from JavaScript, your Accept-Language from the request header, and your location from your IP. When those sources disagree, the disagreement itself is the fingerprint — more telling than any single value.
Timezone vs IP timezone
Your browser’s Intl timezone against the timezone your IP’s location implies. The headline check.
Offset vs IP offset
The UTC offset now, which catches “same offset, different zone” — a weaker but still readable mismatch.
Language vs IP country
Your primary language against your IP’s country. Advisory: travel and expats make this a soft signal, not proof.
Accept-Language vs navigator.languages
The header your browser sent against the list JavaScript reports. These must agree; a difference is a spoofing artefact.
Make the clock follow the exit
A VPN or proxy that changes your IP but leaves your operating-system clock and language alone is the classic half-match. Set the browser’s timezone, locale and language to the place your IP presents — and keep them together as you change exits. Doing that by hand across many profiles is error-prone, which is why Mosaic sets all three from the measured exit automatically.
- Open the checker. The page reads your browser timezone, UTC offset and languages, and asks our server for the timezone and country of your IP.
- Compare the four lines. It compares timezone against IP timezone, offset against IP offset, language against IP country, and your Accept-Language header against navigator.languages.
- Read the consequence. Each line is a fact and a plain consequence — whether a site comparing the two would see one place or two.
What is an IP timezone mismatch?
When your browser’s timezone does not match the timezone of your IP address’s location. A site that reads both — the clock from JavaScript, the location from your IP — sees them disagree, which is one of the first things a consistency scanner checks.
Is a language that differs from my IP country a problem?
Not on its own — people travel and expats exist, so we show it as advisory. A clearer signal is when your Accept-Language header disagrees with navigator.languages, which no normal browser does and a spoof sometimes causes.
How does Mosaic avoid this?
It measures each profile’s exit and sets the timezone, language and geolocation to match it. With no proxy, a profile matches the computer’s own location and falls back to the machine’s own timezone, never a table.
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