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Browser Extensions · head to head

Greasemonkey vs uBlock Origin

Greasemonkey logo

Greasemonkey

Browser Extensions

The original userscript manager, for Firefox

From
Free
Rated
-
Full reviewWebsite
uBlock Origin logo

uBlock Origin

Browser Extensions

Free, open-source ad content blocker

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.; uBlock Origin cNAME uncloaking of third-party trackers disguised as first-party is only available on Firefox, because the required DNS API does not exist in Chromium
  • They diverge on capability: Greasemonkey covers Userscript execution, uBlock Origin covers Ad blocking.
  • Prices and features above were last checked on 15 September 2026.

Where they differ

Only the attributes on which Greasemonkey and uBlock Origin actually diverge.

Attributes where Greasemonkey and uBlock Origin differ
AttributeGreasemonkeyuBlock Origin
Pricing modelopen-sourcefree
PlatformsFirefoxChrome, Firefox, Edge, Opera
FoundedUnknown2014

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 uBlock Origin

  • Ad blocking
  • Tracker blocking
  • Malware domain blocking
  • Custom filter lists
  • 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 uBlock Origin
  • Automating a repetitive action on a web applicationnot uBlock Origin
  • Adding a missing feature to a site you do not controlnot uBlock Origin
  • Running userscripts on Firefox for Androidnot uBlock Origin
  • Writing and testing your own scripts in the browsernot uBlock Origin

uBlock Origin

  • Ad and tracker blocking in web browsersnot Greasemonkey
  • Privacy protection while browsing the webnot Greasemonkey
  • Reducing bandwidth usage by blocking adsnot Greasemonkey
  • Users seeking open-source browser extensionsnot 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.

uBlock Origin

  • CNAME uncloaking of third-party trackers disguised as first-party is only available on Firefox, because the required DNS API does not exist in Chromium
  • HTML filtering of response bodies requires the webRequest.filterResponseData API, which is only available in Firefox
  • On Chromium-based browsers uBO is not reliably ready at browser launch, so tracker and advertisement payloads can reach already-open tabs before filtering starts
  • Pre-fetch blocking is not reliable on Chromium-based browsers because they give websites precedence over user settings
  • The Chromium build does not use the WebAssembly filtering code paths, because the extra manifest permission would create friction publishing to the Chrome Web Store
  • LZ4 storage compression is Firefox only, and on Chromium in incognito mode IndexedDB resets, so uBO launches with out-of-date filter lists

Pricing, plan by plan

Greasemonkey

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

uBlock Origin

Free
  • FreeFree
    • Ad blocking
    • Tracker blocking
    • Custom filter lists

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 uBlock Origin if

  • You need ad blocking.
  • You want to start without paying.
  • You work on Chrome, Firefox, Edge, Opera.
  • You also want tracker blocking.
uBlock Origin review

Questions people ask

Is Greasemonkey or uBlock Origin better?
Neither clearly leads. Greasemonkey starts at Free and uBlock Origin at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Greasemonkey or uBlock Origin?
Greasemonkey starts at Free and uBlock Origin at Free.
Does Greasemonkey or uBlock Origin run on more platforms?
Greasemonkey runs on Firefox. uBlock Origin 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 uBlock Origin is typically brought in for.
What can Greasemonkey do that uBlock Origin cannot?
Greasemonkey covers Userscript execution, Built-in script editor, GM. API, @resource support. uBlock Origin covers Ad blocking, Tracker blocking, Malware domain blocking, Custom filter lists.

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
uBlock Origin: How much does uBlock Origin cost?

uBlock Origin is completely free and open-source software with no licensing fees, subscriptions, or commercial restrictions.

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
uBlock Origin: Is uBlock Origin open source?

Yes, uBlock Origin is distributed under the GPL-3.0 License with source code publicly available on GitHub. The project encourages community review and contribution.

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
uBlock Origin: Does uBlock Origin accept donations?

No, uBlock Origin explicitly does not accept donations. The project instead encourages users to support the developers maintaining the filter lists that power the extension.

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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