Incognito mode (private browsing) is a standard feature in all modern browsers. When enabled, the browser doesn’t save browsing history, cookies, or form data after the session ends. While incognito mode is useful for privacy, it can also be a signal in security and anti-bot analytics.
What Is Incognito Mode?
Incognito (or Private/Guest Mode):
- Prevents browser from saving history, cookies, site data, or autofill after the session
- Blocks most persistent browser storage (like localStorage, IndexedDB, service workers)
- Is available in all major browsers (Chrome, Firefox, Edge, Safari, Opera)
Why Detect Incognito Mode?
1. Bot and Fraud Prevention
Bots and automated tools often use incognito mode to avoid detection, bypass login restrictions, or prevent persistent tracking via cookies.
2. Analytics Accuracy
Some sites want to know the percentage of users browsing in incognito mode to:
- Correctly interpret visitor counts, conversion rates, and returning user stats
- Identify suspicious usage patterns (many new “unique” users in a short time may mean bot activity)
3. Sensitive Content and Abuse Monitoring
Incognito mode can be abused to:
- Bypass paywalls, free trials, or voting limits
- Avoid personalized security checks
Why Is Incognito Detection Difficult?
Browser developers intentionally design incognito mode to be hard (or impossible) to detect. Reasons:
- User privacy: Browsers try to avoid “leaking” signals that could reveal private mode.
- Constant updates: Detection tricks often break as browsers patch methods and add countermeasures.
- Different browsers, different methods: Detection techniques may work in Chrome, but not in Firefox or Safari.
How Is Incognito Detection Attempted?
Common (but not always reliable) methods:
- Storage availability: In incognito, certain browser storage (like
FileSystem API, IndexedDB) may be missing or behave differently.
- Quota and resource limits: Browsers often restrict storage quotas in incognito.
- Behavioral differences: Some APIs are disabled or limited.
Even with these checks, false positives and negatives are possible.
Why Incognito Detection Isn’t Always Reliable
- Browser diversity: Each browser handles incognito/private mode differently.
- Constant evolution: What works today may not work after a browser update.
- User privacy commitment: Some browsers (e.g., Firefox) intentionally make detection nearly impossible.
BotBlocker tries to detect incognito mode using a combination of methods, but guarantees neither 100% accuracy nor coverage for all browsers.
When Is Incognito Detection Useful?
- For analytics and anti-fraud signals
- To challenge or restrict suspicious activity that matches known abuse patterns
- To better understand how users interact with your site
FAQ
Can you always detect incognito mode?
No. Some browsers can be detected sometimes, but not always or everywhere.
Does detection violate privacy?
Detection methods do not collect personal data; they just signal a browsing mode.
Should I block incognito users?
Usually not. Use as a signal for further checks, not for outright blocking.
Learn more about BotBlocker detection methods
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