Verdict
Balanced. Tampermonkey is the practical choice for users who need the widest script library and familiar workflow. ScriptCat may suit users exploring alternative userscript manager workflows. Neither is a universally better option — the right choice depends on your existing scripts, compatibility needs, and interface preferences.
Key Differences
- Userscript workflow — Tampermonkey has an established workflow with a large user base; ScriptCat offers a different interface design.
- Script compatibility — Both support similar userscript formats, but testing is recommended when switching managers.
- Browser support — Tampermonkey has wider browser availability; ScriptCat support depends on its current development status.
- Permission review — Both managers require users to review @match and @grant rules in installed scripts regardless of brand.
- Migration effort — Migrating scripts between managers should be done carefully, testing each script individually.
Side-by-side Comparison
| Option | Best For | MV3 | Cost | Open Source | Setup | Main Trade-off |
|---|---|---|---|---|---|---|
| Tampermonkey | Users who need broad userscript compatibility and a familiar workflow | Available (MV3) | Free / Donationware | Partial (core is open source) | Easy | Larger resource usage but more features and a wider script library |
| ScriptCat | Users exploring alternative userscript manager workflows | Check Chrome Web Store listing | Free | Check project source | Easy | Smaller ecosystem; testing recommended when switching from Tampermonkey |
| Violentmonkey | Users who prefer open-source tooling and GitHub Gist sync | Available (MV3) | Free / Open source | Fully open source | Easy | Minimal interface and fewer built-in features |
| Browser bookmarks | Very simple scripts that do not require external libraries | N/A | Free | N/A | Easy | Very limited — no GM_* APIs, no persistent config |
| Random script mirrors | Not recommended for any use case | Unknown | Unknown | Unknown | N/A | Security, permission, and policy risk |
Which One Should You Choose
You need broad userscript compatibility, a familiar workflow, and the widest available script library.
ScriptCat
You are exploring alternative userscript manager workflows and want to test a different option.
You prefer open-source software and want to sync scripts directly through your own GitHub account.
Avoid unknown script mirrors
You are considering unofficial downloads of scripts or managers from unknown sources.
Common Failed Fixes
Trying to: Import every script at once without review
Why it does not work: Migrating a large batch of scripts without individual testing means you cannot identify which script causes problems if something goes wrong.
Safer alternative: Test scripts one at a time after switching managers to verify expected behavior.
Trying to: Assume all userscript managers behave identically
Why it does not work: Different managers handle script execution, permissions, and sync differently. Some scripts may behave unexpectedly after switching managers.
Safer alternative: Review @match and @grant rules for each script, and test on non-sensitive pages first.
Trying to: Ignore @match and @grant permissions
Why it does not work: These rules control where scripts run and what access they have. Ignoring them means you do not know which sites your scripts are active on or what data they can access.
Safer alternative: Review permissions for each script before and after switching managers.
Trying to: Install scripts from unknown mirrors
Why it does not work: Scripts from unknown sources can be modified to include tracking, data collection, or unwanted behavior. Userscripts run with significant browser access.
Safer alternative: Only install scripts from known repositories like Greasy Fork or OpenUserJS, or scripts whose code you have personally reviewed.
Trying to: Keep multiple managers enabled with overlapping scripts
Why it does not work: Running two userscript managers simultaneously causes scripts to run twice on the same pages, leading to conflicts, duplicate behavior, and unexpected results.
Safer alternative: Use one manager at a time. Export scripts from the old manager before switching, and remove the old manager after confirming the new setup works.
Frequently Asked Questions
Sources
- ScriptCat GitHub RepositoryScriptCatPrimary source
Supports: Official source for ScriptCat development and availability
- Tampermonkey GitHub RepositoryTampermonkeyPrimary source
Supports: Official source for Tampermonkey development
- Violentmonkey GitHub RepositoryViolentmonkeyPrimary source
Supports: Official source for Violentmonkey development
- Chrome Extension Permissions OverviewGoogle Chrome DevelopersSecondary source
Supports: Understanding userscript permission implications