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Browser Extensions · head to head

Greasemonkey vs Web Developer

Greasemonkey logo

Greasemonkey

Browser Extensions

The original userscript manager, for Firefox

From
Free
Rated
-
Full reviewWebsite
Web Developer logo

Web Developer

Browser Extensions

Web developer toolbar for browsers

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.; Web Developer the Web Developer browser extension is licensed GPL-3.0 per its GitHub repository (github.com/chrispederick/web-developer), which states 'All files are distributed for free under the terms of the GNU General Public License,' confirming it has no vendor pricing model to compare.
  • They diverge on capability: Greasemonkey covers Userscript execution, Web Developer covers CSS inspection.
  • Prices and features above were last checked on 15 September 2026.

Where they differ

Only the attributes on which Greasemonkey and Web Developer actually diverge.

Attributes where Greasemonkey and Web Developer differ
AttributeGreasemonkeyWeb Developer
Pricing modelopen-sourcefree
PlatformsFirefoxChrome, Firefox, Edge, Opera
FoundedUnknown2003

Identical on both: starting price (Free), 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
  • Built-in script editor
  • GM. API
  • @resource support
  • Script localisation
  • Firefox for Android

Only in Web Developer

  • CSS inspection
  • Form debugging
  • Image analysis
  • Element outlining
  • Chrome support
  • Firefox support
  • Edge support
  • Opera support

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 Web Developer
  • Automating a repetitive action on a web applicationnot Web Developer
  • Adding a missing feature to a site you do not controlnot Web Developer
  • Running userscripts on Firefox for Androidnot Web Developer
  • Writing and testing your own scripts in the browsernot Web Developer

Web Developer

No use cases recorded yet. See the Web Developer review.

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.

Web Developer

  • The Web Developer browser extension is licensed GPL-3.0 per its GitHub repository (github.com/chrispederick/web-developer), which states 'All files are distributed for free under the terms of the GNU General Public License,' confirming it has no vendor pricing model to compare.

Pricing, plan by plan

Greasemonkey

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

Web Developer

Free
  • FreeFree
    • CSS tools
    • Form tools
    • Image tools

Which should you pick?

Choose Greasemonkey if

  • You need userscript execution.
  • You want to start without paying.
  • You work on Firefox.
  • You also want built-in script editor.
Greasemonkey review

Choose Web Developer if

  • You need css inspection.
  • You want to start without paying.
  • You work on Chrome, Firefox, Edge, Opera.
  • You also want form debugging.
Web Developer review

Questions people ask

Is Greasemonkey or Web Developer better?
Neither clearly leads. Greasemonkey starts at Free and Web Developer at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Greasemonkey or Web Developer?
Greasemonkey starts at Free and Web Developer at Free.
Does Greasemonkey or Web Developer run on more platforms?
Greasemonkey runs on Firefox. Web Developer runs on Chrome, Firefox, Edge, Opera.
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 Web Developer is typically brought in for.
What can Greasemonkey do that Web Developer cannot?
Greasemonkey covers Userscript execution, Built-in script editor, GM. API, @resource support. Web Developer covers CSS inspection, Form debugging, Image analysis, Element outlining.

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
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
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
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
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
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