Question 1

Does Claude Code really check my timezone?

Accepted Answer

According to public reverse-engineering reports, when Claude Code talks to a non-official endpoint it reads the OS timezone and proxy hostname, and steganographically encodes the result into its system prompt. The timezone this page reads via Intl.DateTimeFormat is the very same OS timezone.

Question 2

Is this score the exact check Claude runs?

Accepted Answer

No. Only the system timezone maps one-to-one onto Claude's reported mechanism. The other signals are common Chinese-environment fingerprints that correlate with it, so treat the score as an estimate, not a verdict.

Question 3

How do I lower my score?

Accepted Answer

Switch your OS timezone away from China zones such as Asia/Shanghai, move zh-CN off the top of your browser language list, and avoid routing Claude Code through proxies whose hostnames contain flagged domains or AI-lab keywords.

Question 4

Is any data uploaded?

Accepted Answer

No. Every check runs 100% locally in your browser. None of the detected signals are ever sent anywhere.

Question 5

What signals does this tool check?

Accepted Answer

The tool checks 11 browser fingerprint signals: system timezone (weight 26, same as Claude), browser language (20), installed Chinese fonts (17), Intl locale (8), timezone offset (6), emoji rendering style (5), WebGL renderer (5), screen resolution (4), network info (3), browser plugins (3), and privacy signals like DNT/GPC (3).

Question 6

What is Unicode steganography in Claude Code?

Accepted Answer

When Claude Code detects a China user via timezone or proxy hostname, it reportedly encodes this verdict into the system prompt using visually identical Unicode characters — swapping the date separator dash with a slash, and rotating among four look-alike apostrophe variants to encode additional flags.

Blog

How Claude Code Detects China Users: Timezone, Steganography & Proxy Checks

Browser Fingerprinting Explained: 11 Signals That Reveal Your Identity

How to Change Your System Timezone to Avoid Claude Code Detection

Unicode Steganography in Claude Code: How AI Hides Secrets in Plain Text