Change Useragent string without addon (Mozilla browsers)

Why some webpages deny access because I'm not using one of the top four browsers is beyond me...

Anyhow, here's how you can spoof your useragent on all Mozilla-based (Firefox-like) browsers, e.g. Seamonkey, Palemoon etc. - and of course Firefox itself:

  • Enter about:config in your URL bar.
  • Search for "useragent" and make sure you don't already have the required field (or others that might interfere).
  • If not, create a new string entry by right-clicking inside the Preferences list, and call it general.useragent.override.
  • enter a suitable value. How about Firefox 52 for Windows: Mozilla/5.0 (Windows NT 6.3; WOW64; rv:52.0) Gecko/20100101 Firefox/52.0

That's it. According to Mozilla, it might be necessary to do some resetting to make sure the new value takes.

Where to get an up-to-date useragent string?

Searching "useragent", many sites are outdated or just phishing.
Here are some that look slightly better and up-to-date:

What's your browser's current Useragent string?

netcat -l -p 8100 -v
ncat -k -l -p 8100 -v

Then open your browser to and watch the terminal output.