CODEWITHSUNDEEP
javascriptgoogle-chromeincognito-mode
RodeoClown
RodeoClown

Reputation: 13788

Can you determine if Chrome is in incognito mode via a script?

Is it possible to determine if Google Chrome is in incognito mode via a script?

Edit: I actually meant is it possible via user-script, but the answers assume JavaScript is running on a web page. I've re-asked the question here in regards to user scripts.

Upvotes: 141

Views: 116323

Answers (12)

S.Serpooshan
S.Serpooshan

Reputation: 8388

At 2024, the above codes does not work for me. The following solution works in current version of chrome (Chrome 131):

navigator.webkitTemporaryStorage.queryUsageAndQuota(
  function (_, q) {
    const q2 = performance.memory.jsHeapSizeLimit * 2;
    console.log(q < q2 ? "Incognito mode" : "Normal mode");
})

Upvotes: 1

aljgom
aljgom

Reputation: 9129

Update This seems to not be working anymore

This uses a promise to wait for the asynchronous code to set a flag, so we can use it synchronously afterward.

let isIncognito = await new Promise((resolve, reject)=>{
    var fs = window.RequestFileSystem || window.webkitRequestFileSystem;
    if (!fs) reject('Check incognito failed');
    else fs(window.TEMPORARY, 100, ()=>resolve(false), ()=>resolve(true));      
});

then we can do

if(isIncognito) alert('in incognito');
else alert('not in incognito');

Note, to use await you need to be inside an async function. If you're not, you can wrap all your code inside one to be able to

Upvotes: 2

GorvGoyl
GorvGoyl

Reputation: 49180

Other answers seem to be no longer valid in recent chrome versions.

The idea is to find out storage estimates to determine if the tab is incognito or not. Storage size is less for incognito tabs.

Run this code in both normal and incognito window and note down the quota size.

const {quota} = await navigator.storage.estimate();
console.log(quota);

use quota size difference to implement the logic for incognito mode detection.

below logic works for Chrome v105:

const { quota } = await navigator.storage.estimate();

if (quota.toString().length === 10) {
  console.log("gotcha: this is incognito tab"); //quota = 1102885027
} else {
  console.log("this is a normal tab"); //quota = 296630877388
}

Also, look at this solution for much wider support (includes other browsers as well) detectIncognito.ts

demo: https://detectincognito.com/

Upvotes: 1

nikksan
nikksan

Reputation: 3471

Here is the suggested answer written in ES6 syntaxt and slightly cleand up.

const isIncognito = () => new Promise((resolve, reject) => {
    const fs = window.RequestFileSystem || window.webkitRequestFileSystem;
    
    if (!fs) {
        reject('Cant determine whether browser is running in incognito mode!');
    }

    fs(window.TEMPORARY, 100, resolve.bind(null, false), resolve.bind(null, true));
});

// Usage
isIncognito()
    .then(console.log)
    .catch(console.error)

Upvotes: 0

Ivan Kuckir
Ivan Kuckir

Reputation: 2549

This works in May 2021: https://jsfiddle.net/2b1dk8oa/

The script has to be executed in a webpage, which is in an iframe.

try{
    var ls = localStorage;
    alert("You are not in Incognito Mode.");
}
catch(e) {  alert("You are in Incognito Mode.");  }

Upvotes: -5

Joe Rutkowski
Joe Rutkowski

Reputation: 296

For those looking for a solution, here's a brief rundown of the current methods of detecting Private Browsing modes in various browsers as of October 2021:

  • Chromium: Similar to Vinnie James's answer, call navigator.storage.estimate(), grab the quota property and compare it to performance.memory.jsHeapSizeLimit. If the quota property is less than jsHeapSizeLimit, it's incognito. If jsHeapSizeLimit is undefined, use 1073741824 (1 GiB).

  • Safari for macOS: Use safari.pushNotification.requestPermission on a non-existent push server & grab the error. If "gesture" does not appear in the error, it's in private mode.

  • Safari for iOS: Create an iframe & add an error event listener using contentWindow.applicationCache on the iframe. If the error trips, it's in private mode.

  • Firefox: navigator.serviceWorker will be undefined in a private window.

  • Internet Explorer: window.indexedDB will be undefined in InPrivate mode.

You can see an implementation of these methods in the detectIncognito script I have available on GitHub.

Upvotes: 6

Alok
Alok

Reputation: 3143

The functionality of this answer is Chrome version dependant. The most recent comment was this works in v90

Yes. The FileSystem API is disabled in incognito mode. Check out https://jsfiddle.net/w49x9f1a/ when you are and aren't in incognito mode.

Sample code:

    var fs = window.RequestFileSystem || window.webkitRequestFileSystem;
    if (!fs) {
      console.log("check failed?");
    } else {
      fs(window.TEMPORARY,
         100,
         console.log.bind(console, "not in incognito mode"),
         console.log.bind(console, "incognito mode"));
    }

Upvotes: 254

aljgom
aljgom

Reputation: 9129

Quick function based on Alok's Answer (note: this is asynchronous)

Update - not working anymore

function ifIncognito(incog,func){
    var fs = window.RequestFileSystem || window.webkitRequestFileSystem;
    if (!fs)  console.log("checking incognito failed");
    else {
        if(incog) fs(window.TEMPORARY, 100, ()=>{}, func);
        else      fs(window.TEMPORARY, 100, func, ()=>{});
    }
}

usage:

ifIncognito(true,  ()=>{ alert('in incognito') });
// or
ifIncognito(false, ()=>{ alert('not in incognito') });

Upvotes: 0

Vinnie James
Vinnie James

Reputation: 6042

In Chrome 74 to 84.0.4147.135 you can determine this by estimating the available file system storage space

See the jsfiddle

if ('storage' in navigator && 'estimate' in navigator.storage) {
    const {usage, quota} = await navigator.storage.estimate();
    console.log(`Using ${usage} out of ${quota} bytes.`);

    if(quota < 120000000){
        console.log('Incognito')
    } else {
        console.log('Not Incognito')
    }   
} else {
    console.log('Can not detect')
}

Upvotes: 26

Kinlan
Kinlan

Reputation: 16597

If you are developing an Extension then you can use the tabs API to determine if a window/tab incognito.

More information can be found here.

If you are just working with a webpage, it is not easy, and it is designed to be that way. However, I have noticed that all attempts to open a database (window.database) fail when in incongnito, this is because when in incognito no trace of data is allowed to be left on the users machine.

I haven't tested it but I suspect all calls to localStorage fail too.

Upvotes: 5

JHurrah
JHurrah

Reputation: 1988

One way is to visit a unique URL and then check to see whether a link to that URL is treated as visited by CSS.

You can see an example of this in "Detecting Incognito" (Dead link).

Research paper by same author to replace Detecting Incognito link above

In main.html add an iframe,

 <iframe id='testFrame' name='testFrame' onload='setUniqueSource(this)' src='' style="width:0; height:0; visibility:hidden;"></iframe>

, and some JavaScript code:

function checkResult() {
  var a = frames[0].document.getElementById('test');
  if (!a) return;

  var color;
  if (a.currentStyle) {
    color = a.currentStyle.color;
  } else {
    color = frames[0].getComputedStyle(a, '').color;
  }

  var visited = (color == 'rgb(51, 102, 160)' || color == '#3366a0');
  alert('mode is ' + (visited ? 'NOT Private' : 'Private'));
}

function setUniqueSource(frame) {
  frame.src = "test.html?" + Math.random();
  frame.onload = '';
}

Then in test.html that are loaded into the iFrame:

<style> 
   a:link { color: #336699; }
   a:visited { color: #3366A0; }
</style> 
<script> 
  setTimeout(function() {
    var a = document.createElement('a');
    a.href = location;
    a.id = 'test';
    document.body.appendChild(a);
    parent.checkResult();
  }, 100);
</script>

NOTE: trying this from the filesystem can make Chrome cry about "Unsafe Javascript". It will, however, work serving from a webserver.

Upvotes: 20

Igor Zevaka
Igor Zevaka

Reputation: 76500

You can, in JavaScript, see JHurrah's answer. Except for not highlighting links, all incognito mode does is not save browse history and cookies. From google help page:

  • Webpages that you open and files downloaded while you are incognito aren't recorded in your browsing and download histories.
  • All new cookies are deleted after you close all incognito windows that you've opened.

As you can see the differences between normal browsing and incognito happen after you visit the webpage, hence there is nothing that browser communicates to the server when it's in this mode.

You can see what exactly your browser sends to the server using one of many HTTP request analysers, like this one here. Compare the headers between normal session and incognito and you will see no difference.

Upvotes: 7

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