别用排名第一第二的useragent插件了
这个最牛B了
首先多，各平台各新旧版本
再来就是黑名单白名单自定义规则太强大

来使用百度简单搜索APP的useragent来访问百毒看看
Mozilla/5.0 (Linux; Android 7.0; wv) AppleWebKit/537.36 (KHTML, like Gecko) Version/4.0 Chrome/48.0.2564.116 Mobile Safari/537.36 T7/10.3 SearchCraft/2.6.2 (Baidu; P1 7.0)

これから楽しみです。他のブラウザでは楽しんでいます。

Opens a tab at the far right containing a webpage asking for money(donations), then shows google ads in there.

すごく良い
非常に見やすいUIで、メジャーなOSはほとんど揃っていて、ブラウザも最新ブラウザでない限りある程度揃っている。
直接編集も可能
javascriptにもちゃんとカスタムUAが聞いている強力なUAスイッチャーです。

Nice extension, can switch what i use now to diffrent

This appears to be an effective agent switcher, I like it but there's just one thing, I can't set the screen resolution to something different than what my actual screen resolution is. If you could add in an option for spoofing the screen resolution this would be a 5/5 add-on :-)

Minimal, under 1 MB (not like other extensions which can be up to 8 MB for no reason). Works as expected, great UI. Thank you for developing this, it's a far better option to the more popular extensions.

I love this add-on!
With the recent onset of Apple enforcing its "proprietary" right to use the emojis we are all used to, Slack, et al were forced to switch to their own, non-Apple Color Emoji typeface -- and if you're like me, they're HIDEOUS emojis. This extension allows me to permanently spoof the user agent to an iOS device for specific sites where I use emojis a lot. Like Slack, fb, etc.
When I was using Chrome browser, I could only achieve this by CTRL+I and de-toggling "Select automatically" under the Network Conditions sub-menu inside dev tools. So this permanent fix in Firefox is exactly what I wanted.

浏览器标识切换工具。我觉得选项太多了，其实只要苹果，windows，IOS，安卓几个主流的就行了。

I usually install the most downloaded add-on. Not this time. I installed the best rated one. And I don't regret it one sec. Very good, intuitive Firefox extension.

This app is so helpful.

This is easily the best user agent switcher I've tried. It has the most comprehensive and most customizable list of browsers and operating systems to choose from, and is the only one that I have found with the ability to set the user agent on a per-site basis in Quantum, which makes it even more powerful. Thanks!

Very good addon to go past google search filter limitations when using firefox android browser. I use it to whitelist google domains and load the chrome android user agent when doing google searches so i can have all filters.

Text in dropdown is the same colour as the background, making it unreadable.
Edit: Fixed

I used the Chrome string and was able to login to Directvnow. I am able to watch in Firefox rather than stupid Chrome. I will donate soon.

This is the best useragent switching addon.

Works well with Firefox Nightly v60.0a1 on Android v6.0.1. Would be vastly improved if regular expressions (extended form) could be used to match against entire URLs. Currently, only the absolute string of the top-level hostname can be checked. But with regular expressions, it would, for example, be possible to match "^[fhttps]*\:\/\/www\.google\.co(m|\.[^\/]*)\/imgres\?" against URLs, in order to specify the user agent for displaying an image returned from a Google image search. Although this is a seemingly-specific example, with extended regular expression matching, anything would be possible, as they provide maximum URL-matching flexibility.