This is the superior userscript manager. It's free & open source, it works perfectly, and has frequent updates. Goodbye tampermonkey, rip Greasemonkey (hasn't worked right in years).

A great, modern alternative to Greasemonkey, also in terms of the supported API. And it's open source (unlike Tampermonkey), which I consider pretty important for an extension that can access and modify every page you visit!

Excelente extensão

Thanks for you work.

This is my favourite primate in the world! It is a solution to my browser woes.
Thankyou!

Fantastico