# GreatFire

> GreatFire measures censorship by the Great Firewall of China. For any website or URL it reports whether it is blocked in mainland China, since when, by what mechanism (DNS poisoning, connection reset, redirection to a Chinese site), and the underlying US/CN test data.

## Check a URL
- Verdict page: https://en.greatfire.org/https/<host><path> — e.g. https://en.greatfire.org/https/facebook.com
- JSON verdict for any page: put /api/url/ in front of its path — e.g. https://en.greatfire.org/api/url/https/facebook.com
- A verdict is one of: blocked, redirected (to a Chinese site), intermittent, not blocked, or not enough data. The headline percentage is the share of conclusive tests blocked over the last 90 days.

## API (JSON)
- https://en.greatfire.org/api/verdict?path=https/facebook.com — verdict + 90-day stats + per-test history
- https://en.greatfire.org/api/search?q=facebook — ranked search + related URLs
- https://en.greatfire.org/api/domain?registrable=facebook.com — every tested host under a domain
- https://en.greatfire.org/api/test?id=<id> — the raw US/CN measurement rows for one test

## Key pages
- https://en.greatfire.org/analyzer — home / search
- https://en.greatfire.org/blocked — currently and notably blocked sites
- https://en.greatfire.org/explore — browse every tested URL by interference mechanism or status
- https://en.greatfire.org/trends — site-wide statistics and blocked-by-TLD breakdown
- https://en.greatfire.org/top-sites-china — the 1,000 most-visited websites (Tranco) and whether each is reachable from mainland China
- https://en.greatfire.org/data — dataset description and full endpoint list
- https://en.greatfire.org/data/methodology — how the tests and verdicts work, and their limits
- https://en.greatfire.org/faq — how this site tests, what its verdicts mean, what they cannot tell you
- https://en.greatfire.org/vpns-proxies — looking up circumvention tools' own websites; tool rankings live at https://cc.greatfire.org

## Methodology
Each URL is fetched from control (US) and in-country (CN) vantage points. Rows are compared to decide the mechanism: DNS poisoning (CN resolves to a poisoned/mismatched IP), connection reset (CN connection fails while US succeeds), redirection to a Chinese site, or an empty/blocked response. Each detector is gated on the evidence it needs: if the control's own transfer fails, the DNS, reset and redirect checks still apply, but such a test can only convict, never clear a URL. Full detail: https://en.greatfire.org/data/methodology

## About
GreatFire has monitored the Great Firewall since 2011. To bypass it, see GreatFireVPN: https://greatfirevpn.com