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Browser Extensions · head to head

Greasemonkey vs Userscripts

Greasemonkey logo

Greasemonkey

Browser Extensions

The original userscript manager, for Firefox

From
Free
Rated
-
Full reviewWebsite
Userscripts logo

Userscripts

Browser Extensions

Open-source userscript manager for Safari on Mac and iOS

From
Free
Rated
-
Full reviewWebsite

The short version

  • Each has a real cost: Greasemonkey firefox only. There is no Chrome, Edge or Safari build and there never has been.; Userscripts safari cannot let extensions bypass a site's Content Security Policy, so strict sites produce "Refused to execute a script" errors that the @inject-into workaround does not always fix.
  • They diverge on capability: Greasemonkey covers Userscript execution, Userscripts covers Standard metadata support.
  • Prices and features above were last checked on 15 September 2026.

Where they differ

Only the attributes on which Greasemonkey and Userscripts actually diverge.

Attributes where Greasemonkey and Userscripts differ
AttributeGreasemonkeyUserscripts
PlatformsFirefoxSafari, macOS, iOS

Identical on both: starting price (Free), pricing model (open-source), free tier (Yes), user rating (Not yet rated), category (Browser Extensions).

What each one covers

Drawn from each product's published feature list. An absence here means we hold no record of it - not that the product lacks it.

Only in Greasemonkey

  • Userscript execution
  • GM. API
  • @resource support
  • Script localisation
  • Firefox for Android

Only in Userscripts

  • Standard metadata support
  • GM API
  • Remote script updating
  • iCloud sync
  • Per-page popup

Both cover

  • Built-in script editor

What people use each for

The jobs each tool is most often brought in to do.

Greasemonkey

  • Restyling or de-cluttering a site you use dailynot Userscripts
  • Automating a repetitive action on a web applicationnot Userscripts
  • Adding a missing feature to a site you do not controlnot Userscripts
  • Running userscripts on Firefox for Androidnot Userscripts
  • Writing and testing your own scripts in the browsernot Userscripts

Userscripts

  • Running userscripts on Safari without paying for Tampermonkeynot Greasemonkey
  • Running userscripts on an iPhone or iPadnot Greasemonkey
  • Writing scripts on a Mac and syncing them to iOSnot Greasemonkey
  • Blocking or restyling site elements Safari content blockers cannot reachnot Greasemonkey
  • Keeping a script library under an open-source licencenot Greasemonkey

Where each one falls short

Documented limitations, not opinions. Every one is a constraint you would hit in normal use.

Greasemonkey

  • Firefox only. There is no Chrome, Edge or Safari build and there never has been.
  • Its API diverged from the Tampermonkey conventions most shared scripts are written against, so a script from a sharing site may need adjusting to run.
  • The dashboard is plainer than Tampermonkey's, with no diff view when a script updates itself.
  • No cloud sync of the kind Tampermonkey and Violentmonkey offer; moving machines means exporting.
  • A userscript manager can read and rewrite every page you visit, so the security of the arrangement depends entirely on the scripts you choose to install.

Userscripts

  • Safari cannot let extensions bypass a site's Content Security Policy, so strict sites produce "Refused to execute a script" errors that the @inject-into workaround does not always fix.
  • Apple only. There is no Chrome, Firefox or Edge build, so it cannot be a cross-browser answer.
  • iCloud sync is documented as having delays, which is awkward when editing the same script on two devices.
  • Requires macOS 12 and Safari 14.1, or iOS 15.1, so older Apple hardware is excluded.
  • GPL v3 means a commercial licence is required for non-open-source use, which matters if you are embedding rather than just using it.

Pricing, plan by plan

Greasemonkey

Free
  • Open sourceFree
    • Unlimited scripts
    • Built-in editor
    • No account required

Userscripts

Free
  • FreeFree
    • Full functionality
    • GPL v3 licensed
    • macOS, iOS and iPadOS

Which should you pick?

Choose Greasemonkey if

  • You need userscript execution.
  • You want to start without paying.
  • You work on Firefox.
  • You also want gm. api.
Greasemonkey review

Choose Userscripts if

  • You need standard metadata support.
  • You want to start without paying.
  • You work on Safari, macOS, iOS.
  • You also want gm api.
Userscripts review

Questions people ask

Is Greasemonkey or Userscripts better?
Neither clearly leads. Greasemonkey starts at Free and Userscripts at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Greasemonkey or Userscripts?
Greasemonkey starts at Free and Userscripts at Free.
Does Greasemonkey or Userscripts run on more platforms?
Greasemonkey runs on Firefox. Userscripts runs on Safari, macOS, iOS.
Can I use Greasemonkey for free?
Both have a free tier, so you can try either at no cost before committing.
What is Greasemonkey best used for?
Greasemonkey is most often used for restyling or de-cluttering a site you use daily, automating a repetitive action on a web application, adding a missing feature to a site you do not control, running userscripts on firefox for android. Of those, restyling or de-cluttering a site you use daily and automating a repetitive action on a web application are not what Userscripts is typically brought in for.
What can Greasemonkey do that Userscripts cannot?
Greasemonkey covers Userscript execution, GM. API, @resource support, Script localisation. Userscripts covers Standard metadata support, GM API, Remote script updating, iCloud sync. Both handle Built-in script editor.

Answered from the vendors’ own pages

Greasemonkey: Is Greasemonkey still maintained?

Yes. Version 4.14 was released on 2 June 2026, and the project has an active repository, bug tracker and discussion groups.

Source
Userscripts: Is Userscripts for Safari free?

Yes, free on the App Store and licensed under GPL v3. A commercial licence is required for use in something that is not itself open source.

Source
Greasemonkey: Does Greasemonkey work on Chrome?

No. It is a Firefox extension and has never shipped for Chrome. Violentmonkey and Tampermonkey are the equivalents there.

Source
Userscripts: Does it work on iPhone?

Yes, on iOS and iPadOS 15.1 or later, which makes it one of the few ways to run userscripts on an iPhone.

Source
Greasemonkey: Will Tampermonkey scripts run in Greasemonkey?

Often, but not always. Greasemonkey's API diverged from the conventions most shared scripts are written against, so a script may need its header or its GM calls adjusted.

Source
Userscripts: Why do I get "Refused to execute a script" errors?

Safari does not let extensions bypass a site's Content Security Policy the way other browsers do. The documented workaround is changing the script's @inject-into setting, though it does not resolve every case.

Source
Greasemonkey: Does Greasemonkey run on mobile?

On Firefox for Android, from version 4.12. There is no iOS build, because Firefox on iOS cannot load extensions of this kind.

Source
Userscripts: Do my scripts sync between Mac and iPhone?

Yes, over iCloud, though the project notes the sync can be delayed rather than immediate.

Source
Greasemonkey: What is the GM API?

The set of functions a userscript manager exposes to scripts, named after Greasemonkey, which defined it. Greasemonkey supports the promise-based GM. form including GM.xmlHttpRequest and GM.registerMenuCommand.

Source
Userscripts: What are the system requirements?

macOS 12 or later with Safari 14.1 or later, or iOS and iPadOS 15.1 or later.

Source
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