Tampermonkey Alternatives Page

Greasemonkey is the original user-script manager. Before Tampermonkey existed, there was Greasemonkey. However, it has fallen out of favor due to architectural changes in Firefox (WebExtensions).

In addition to JavaScript userscripts, it natively supports custom user CSS (userstyles). 4. Userscripts (For Safari and iOS Users) tampermonkey alternatives

Only install scripts from trusted authors, as they can access data on the websites you visit. Greasemonkey is the original user-script manager