Tool to verify my proxies

I remember there was a tool with a really nice UI that could verify multiple proxy connections. Its name had a lot of major letters (like LNTNSNT)

There are tons of proxy checkers online,check out github and softopedia also has good ones too.

How many proxies do you need to test/verifiy?

You are always better off testing a few proxies (if you have access to a large IP pool) via your browser. The good old fashion way of proxy in browser and accessing websites (not making simple requests for reading its code).