Free tool
Browser privacy check
Every site can read these details without asking. Together they help sites recognize your browser even without cookies.
Opt-out signals
Global Privacy Control (GPC) is a browser setting that tells sites you don't want your data sold or shared. Under California's privacy regulations businesses must treat it as a valid opt-out, and several other US states recognize it too. Firefox, Brave and DuckDuckGo's browser support it; in Chrome it needs an extension.
Do Not Track (DNT) is an older signal with the same aim. No law required sites to honor it and most ignored it, so it now does little. Some browsers have dropped it.
Fingerprinting: why the other details matter
Your time zone, languages, screen size, number of processor threads, graphics card and user agent are each shared by many people. Combined, they can single out a browser, a technique called fingerprinting. Unlike a cookie, a fingerprint can't be cleared. Tor Browser and Mullvad Browser fight it by making every user look the same. Brave and Firefox add noise or block known fingerprinting scripts. See private browsers.
What you can do
- Turn on Global Privacy Control, or use a browser that sends it.
- Block third-party cookies, which most privacy-focused browsers do by default.
- Use a browser with fingerprinting protection, such as Firefox with strict tracking protection, Brave, Mullvad Browser or Tor Browser.
- Keep in mind that a VPN changes your IP address but not your fingerprint. The two protect against different things.
Questions people ask
Is Global Privacy Control legally binding?
For businesses covered by California's privacy law, yes: its regulations require them to treat GPC as a request to opt out of the sale or sharing of personal information. Some other US states, such as Colorado, also require universal opt-out signals to be honored. Elsewhere it depends on local law.
Does incognito mode stop fingerprinting?
No. Private or incognito windows don't keep cookies and history after you close them, but they show the same device details to sites.
Sources
- Global Privacy Control: specification and supporting browsers (globalprivacycontrol.org) · read November 13, 2026
- California Attorney General: CCPA FAQ (opt-out preference signals) (oag.ca.gov) · read November 13, 2026
- Colorado Attorney General: Universal opt-out mechanism (coag.gov) · read November 13, 2026
- EFF: Cover Your Tracks (browser fingerprinting) (coveryourtracks.eff.org) · read November 13, 2026