Regex for replacing parameter values in a URL (values between = and &)

Question

I have a large list (100,000+) of URLS with parameters like so:

https://www.example.com?a=b&1=2&me=you
https://www.example.com?a=b

I'm using VIM need a regex to replace all values with whatever I desire, like so:

https://www.example.com?a=value&1=value&me=value
https://www.example.com?a=value

Also, I'm not limited to a Regex, if someone has a solution using norm or sed, that would also work. I just need to be able to automate it.

Answer 1

Quasimodo commented the solution, so I'll post here so I can mark this answered:

To replace each value between = and &, and everything after the final =, if it's the last parameter in a URL, for every line in a file, this works:

%s/\([^&?]*=\)[^&]*/\replacement/g