detectIncognito.js

Note: Detection is broken for Chromium 147+ due to predictable-reported-quota being enabled by default (see Issue #49)

Efficiently detect Incognito mode & other private browsing modes across most modern browsers.

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Features

• ✅ Incognito detection on Google Chrome (see notes)
• ✅ Private Window detection on Safari (macOS)
• ✅ Private Tab detection on Safari (iOS)
• ✅ Private Window detection in Firefox
• ✅ InPrivate Window detection on Microsoft Edge
• ✅ InPrivate Window detection on Microsoft Internet Explorer
• ✅ Private Window detection in Brave (see notes)
• ✅ Private Window detection in Opera

Demo

Check out the live demo.

Usage

Get the script from CDN (may be blocked by adblockers—see notes):

<script src="https://cdn.jsdelivr.net/gh/Joe12387/detectIncognito@main/dist/es5/detectIncognito.min.js"></script>

Or install via NPM:

npm i detectincognitojs

import { detectIncognito } from "detectincognitojs";

detectIncognito().then((result) => {
  console.log(result.browserName, result.isPrivate);
});

Supported Browsers

Browser	Platform(s)	Versions	Notes
Safari	All	≤ 26.4
Chromium	All	50 to 146	Detection broken by predictable-reported-quota flag (Issue #49)
Firefox	All	44 to 151
MSIE	Windows	11	Requires Promise polyfill

Notes

• False positives can occur in certain browser setups or Chrome Guest mode (Issue #21).
• Firefox Container Tabs aren't detected by this.
• The script must run over HTTPS—running locally or via HTTP might fail.
• Brave and uBlock Origin block the CDN; hosting the script yourself avoids this issue.
• An error is thrown if the browser can't be identified.

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License

Copyright © 2026 Joe Rutkowski
Distributed under the MIT License.