this is exactly what I need, thank you!

Лучший на сегодня.
Best for today.

I really like Random User-Agent
I can not use the Random User-Agent on a site it is often detect and the site blocks me I would like to know the different settings to be more efficient with.

Thank you for your reply

在Android手机上（大约firefox 63开始）性能不良：我勾选safari on iphone，发现失灵后禁用再启用才会正常。

Works as well as any other User-Agent Swithcer, BUT...!
But the settings are super simple and straightforward to understand and to set up automated switching. That's why I chose this add-on before the other options!

I love this extension as it handles the job of altering UA automatically (set up and forget plugin), but now for whatever reason it doesn't save domain preferences so I have to disable it on custom domains (like youtube else the page won't show) every time. I would like to put 5 stars if this issue is corrected, for me its still the best plugin for that application.

EDIT : I think its just the exception list that is reset; maybe after update of the plugin (autoupdate is on, I will disable it to check)

Works great! I especially love the statistically inconspicuous pool of agents. It still provides a reasonable deal of slight even if you have to set it to a selection of a specific operating system and browser to prevent constant broken websites. For me this is an acceptable alternative to constantly curating a white-list.