Google Chrome and Mozilla Firefox come with built-in features that allows users to change default user agent, however, it is not possible to define a particular user agent on a per-site basis. If you want such a functionality, have a look at User-Agent Switcher for Chrome and UAControl for Firefox – both these extensions allow you to set specific user agents for certain domains you want.
User-Agent Switcher for Chrome
Install the extension from Chrome Web Store and head over to its settings –
chrome-extension://djflhoibgkdhkhhcedjiklpkjnoahfmg/options.html. In the left menu, click on Permanent Spoof List.
Then enter the domain of the particular website, choose the desired user agent you want to assign from the dropdown menu, and click on Add. That’s it. Refresh the page and you should see your selection in effect. Extension icon in the Chrome menu shows the active profile.
All specified domain are listed below the form, from there you can delete it later if you want.
UAControl for Firefox
Install UAControl and restart Firefox to enable the add-on. After restart, go to Firefox menu > Add-ons > UAControl > Options. This will open a dialog window as seen below:
Here, click on Add Site, enter site domain, choose Custom and enter the custom user agent you want, and hit OK to save changes.
Unlike the extension for Chrome, in UAControl you need to manually enter user agents. If you need a list of that, have a look at
useragentstring.com. On this site you will find user agent strings for crawlers, web browsers, mobile browser, link checkers, and a lot more.
That’s all. After the initial setup process you don’t have to worry about these settings anymore. You can continue using your browser as you normally do, and websites would behave the way you chose.