Greasemonkeyvs
Violentmonkey
Violentmonkey: Open source and also on Firefox, with wider compatibility for scripts written against modern Tampermonkey conventions, plus Chrome and Edge builds Greasemonkey has never had.
Greasemonkey
The original userscript manager, for Firefox
As of 15 September 2026, Greasemonkey is free to use. The userscript manager that started the category. Softwr lists it under Browser Extensions. Greasemonkey is available on Browser extension.
Overview
What Greasemonkey does
Greasemonkey is the Firefox extension that created the userscript category and gave it its vocabulary. Every other manager in this space implements an API that begins with the letters GM because Greasemonkey defined it, and script headers written twenty years ago still use directives it introduced. It does one thing: it lets you run small JavaScript files of your own choosing against pages you visit, so a site can be restyled, de-cluttered, automated or extended without waiting for its owner. It ships a script editor with syntax highlighting, supports the promise-based GM. functions including GM.xmlHttpRequest and GM.registerMenuCommand, handles @resource files and allows script localisation through @name and @description metadata. It is Firefox only and has been throughout. Version 4.12 added support for Firefox on Android; the current release is 4.14, published on 2 June 2026, so the long-running claim that the project is abandoned is simply wrong. What is true is that its API diverged from the Tampermonkey-flavoured norm that most modern scripts are written against, so a script found on a sharing site may need adjusting in a way it would not under Violentmonkey.
What people use it 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
- Writing and testing your own scripts in the browser
The honest half
Where it falls short
Concrete and checkable, so you can decide whether any of them matter to you. This is the half of a review a vendor will not write about 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.
Cross-shopped
What people choose instead of Greasemonkey
Each pairing was judged by two reviewers asking whether a buyer would genuinely weigh the two against each other. The ones that failed were deleted rather than published.
- GreasemonkeyvsTampermonkey
Tampermonkey: The most widely targeted manager, with a richer dashboard and a diff view on script updates, though it is closed source and runs on more browsers.
Pricing
What Greasemonkey costs
Taken from the vendor's own pricing page. Prices move, so check before you buy.
Open source
Free
- Unlimited scripts
- Built-in editor
- No account required
Capabilities
Features
Userscript execution
Runs user-supplied JavaScript against matching pages, the function the entire category is named after.
Built-in script editor
Edit scripts in the browser with syntax highlighting, without an external editor.
GM. API
The promise-based script API including GM.xmlHttpRequest for cross-origin requests and GM.registerMenuCommand for adding entries to the monkey menu.
@resource support
Bundle and reference external files with a script rather than fetching them at runtime.
Script localisation
Localised @name and @description metadata, so a script can present itself in the reader's language.
Firefox for Android
Runs on Firefox for Android from version 4.12, one of the few managers that does.
Answered, with sources
Questions people ask
Each answer names the page it came from, so you can check it rather than take our word for it.
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.
SourceDoes Greasemonkey work on Chrome?
No. It is a Firefox extension and has never shipped for Chrome. Violentmonkey and Tampermonkey are the equivalents there.
SourceWill 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.
SourceDoes 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.
SourceWhat 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.
SourceKeep looking
Where to go from Greasemonkey
- Greasemonkey alternativesEvery product people weigh against it
- Greasemonkey pricingPlans, floors and what the tiers exclude
- Greasemonkey badgesWhich rules it meets, and the figure behind each
- All Browser Extensions softwareThe full category
- Best Browser Extensions softwareThe shortlist, and how it was cut
Best Browser Extensions software for
Compare Greasemonkey with
- FireMonkey
- Violentmonkey
- Tampermonkey
- Userscripts
- Stay
- Raindrop.io
- Keeper
- Mercury Reader
- Stylus
- Dark Reader
- Privacy Badger
- Rakuten
- uBlock Origin
- Hemingway Editor
- Night Eye
- React Developer Tools
- Save to Google Drive
Other Browser Extensions software
Safari userscript manager that runs Tampermonkey scripts
Free, then $5/one-time12 researched notes
Softwr does not host reviews and shows no star rating for Greasemonkey, because a rating we did not collect is not ours to publish. What is here is the pricing and platform detail from the vendor’s own pages, limitations we could state concretely, and alternatives a reviewer confirmed people weigh against it. Tell us if any of it is wrong.
More on Greasemonkey
Greasemonkey alternatives
What people switch to, and what they give up
Greasemonkey pricing
Every tier, and where the cost actually lands
Compare Greasemonkey
Put it head to head with anything we hold
Greasemonkey badge
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