Doesn't work anymore, no updates in sight to fix this.

Amazing, fixed a myriad of youtube playback issues using the developers guide.

Very small text.
All English. It can not use.
Not found “OK” button.
No visual design.
Color Design so bad.


文字が小さすぎる。
全部英語。
利用者の母語がない。
視覚設計・色彩設計がない。
「ＯＫ」「適用」ボタンがない。
使うことができない。

Setting pange: One line text fills the screen to the left and right edges.
「設定」ページが長文。１行＝画面左右の端まで。

「テストUA」クリック→ほかの長文サイトが開く。
h　ttps://webbrowsertools.com/useragent/?method=normal&verbose=false

I recently started testing this extension. The last version "improved" the extension so much that it stopped working. It doesn't matter what user-agent it shows - browser tests always return the original one.

Need support for Android

After switching user agents I wasn't able to get this add-on working. The menu is over complicated and not clear at all. Also, it's impossible to know weather you have changed or not the user agent because the icon or the menu doesn't tell you at all.

User-Agent Switcher by ntninja is way clearer, and worked at first try. You can know at any moment whether there is user agent switch or not by just looking at the icon. That add-on also works on Firefox Android.

▫️📂☠️▪️

Why is this extension spoofing youtube when it is not set to do so?

Bizarrely over complicated. The ntninja switcher let's you just pick a user agent and go. Never got this one to work.

It works regularly in Mozilla Firefox 129.0B9 X64. It is a pity that manual editing of a list of comparison of domains and UA is carried out only in JSON format, and not in something more accessible to non-specialists.

Upd. 0.6.6 (Oct 8, 2025) and Mozilla Firefox 148.0b12:

1. Selected "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/142.0.0.0 Safari/537.36" from the list.
2. Clicked "Apply (all tabs)".
3. Clicked "Test UA".
4. webbrowsertools.com: "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:148.0) Gecko/20100101 Firefox/148.0".

The extension does not perform its main function.