Tampermonkey is a popular userscript manager for Chrome, Microsoft Edge, Safari, Opera Next, and Firefox. If you're looking for alternatives, here are some options:
Which userscript manager should I choose these days? : r/firefox tampermonkey alternative
(Chrome, Firefox, Edge): Violentmonkey is a userscript manager that's similar to Tampermonkey. It's available for Chrome, Firefox, and Edge. Tampermonkey is a popular userscript manager for Chrome,
Power users who want minimal performance overhead and need to manage both scripts and CSS styling. 4. Userscripts (Safari) it is a closed-source
Tampermonkey is the de facto standard for userscript management, boasting the largest user base and feature set. However, it is a closed-source, commercial product that tracks user usage (analytics) and has a heavy memory footprint.
Open Source | Platforms: Cross-Platform (Node.js environment)
