X in-app browser user agent strings in 2026

X introduced a new in-app browser on iOS and Android that lets you keep the Like, Repost, and other buttons at the bottom of the screen while you open a link.

X tests keeping the original post visible while viewing links, starting with iOS

Nikita Bier, X's head of product, posted on his X account that they are starting an iOS test to let followers easily react to the original post while viewing a link.

October 20, 2025

I checked the user agent strings after X introduced this new in-app browser and wanted to share the results. The information in this article is current as of September 2026.

Android

On a Google Pixel 8 running Android 17, I saw the following user agent string:

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Mozilla/5.0 (Linux; Android 17; Pixel 8 Build/CP31.260623.005; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/151.0.7922.202 Mobile Safari/537.36 TwitterAndroid/12.28.0-alpha.01 (312280201-r-01) Pixel+8/17 (Google;Pixel+8;google;shiba_beta;0;;1;2015)

If you need to detect whether someone is using X’s in-app browser on Android, checking whether the user agent string contains TwitterAndroid should be enough, since the string also contains details such as the device OS.

iOS

I do not own an iOS device, so I inferred the user agent string for X’s iOS in-app browser from my logs.

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Mozilla/5.0 (iPhone; CPU iPhone OS 27_0 like Mac OS X) AppleWebKit/605.1.15 (KHTML, like Gecko) Mobile/24A437 Twitter for iPhone/12.26

If you need to detect whether someone is using X’s in-app browser on iOS, checking whether the user agent string contains Twitter for iPhone should be enough.

Conclusion

I found it curious that X’s iOS app uses Twitter for iPhone in its in-app browser user agent string, while the Android app does not use Twitter for Android.

You should be able to identify X’s in-app browser by checking whether the user agent string contains either TwitterAndroid or Twitter for iPhone.