Incognito Mode Detector
Check for private browsing — and see why browsers deliberately broke this test.
How this test works
The storage quota offered to this origin is read and compared against what an ordinary session usually receives. That is the one detection method that still partly works, and it is worth understanding why it is all that is left: private-browsing detection used to be straightforward, and browsers have systematically removed the methods because sites were using them to block readers rather than to protect anyone. Even this signal is weak — quota shrinks when the disk is nearly full, and several browsers now deliberately report a normal quota in private mode to defeat exactly this check. So the result reports the observation and explicitly declines to turn it into a verdict.
What the results mean
- Storage quota offered
- What the browser will let this origin store. Sharply reduced quota is the surviving hint.
- Storage writable
- Whether writing works at all. Failure used to mean private mode and now usually means a setting or extension.
- Detection reliability
- Low, and falling. Each browser release tends to make it worse.
- Verdict offered
- None. The observation is reported without being converted into a claim.
Common problems and fixes
- It will not tell me if I am in private mode
- Deliberately. The signal is not strong enough to support a claim, and pages that make one anyway are guessing.
- A site blocked me for using private browsing
- That is why browsers keep closing these methods. The detection they used has probably already stopped working.
- My quota is low in a normal window
- Most likely a nearly full disk, which reduces quota independently of private mode. It is the main false positive.
Frequently asked questions
Can websites detect private browsing?
Less and less. Browsers have removed the reliable methods deliberately, because sites were using them to block readers. What remains is a storage-quota heuristic that several browsers now defeat on purpose.
Why did browsers break this detection?
Because it was used against users rather than for them — most visibly by publishers blocking people who opened an article in a private window. Removing the signal was a policy decision, not an oversight.
Does private browsing hide me from websites?
It hides you from other people using the device by not keeping history or storage. It does not hide you from the sites themselves, from your network, or from fingerprinting, which works without storage entirely.