Softwr

Browser Extensions · head to head

Greasemonkey vs ProWritingAid

Greasemonkey logo

Greasemonkey

Browser Extensions

The original userscript manager, for Firefox

From
Free
Rated
-
Full reviewWebsite
ProWritingAid logo

ProWritingAid

Browser Extensions

AI writing assistant and grammar checker

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.; ProWritingAid free plan limited to 500 word count with only 2 report runs per day
  • They diverge on capability: Greasemonkey covers Userscript execution, ProWritingAid covers Grammar checking.
  • Prices and features above were last checked on 15 September 2026.

Where they differ

Only the attributes on which Greasemonkey and ProWritingAid actually diverge.

Attributes where Greasemonkey and ProWritingAid differ
AttributeGreasemonkeyProWritingAid
Pricing modelopen-sourcefreemium
PlatformsFirefoxWeb, Windows, Mac, Chrome, Firefox, Edge
FoundedUnknown2013

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 ProWritingAid

  • Grammar checking
  • Style analysis
  • Readability reports
  • Plagiarism checker
  • Chrome support
  • Firefox support
  • Edge support
  • Safari 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 ProWritingAid
  • Automating a repetitive action on a web applicationnot ProWritingAid
  • Adding a missing feature to a site you do not controlnot ProWritingAid
  • Running userscripts on Firefox for Androidnot ProWritingAid
  • Writing and testing your own scripts in the browsernot ProWritingAid

ProWritingAid

  • Grammar and style checking for writers and authorsnot Greasemonkey
  • Story planning and structure analysisnot Greasemonkey
  • Character and manuscript analysis for fiction writersnot Greasemonkey
  • Integration with Microsoft Word, Google Docs, Scrivener, and Notionnot 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.

ProWritingAid

  • Free plan limited to 500 word count with only 2 report runs per day
  • Advanced AI features (50 Sparks per day, Chapter Critiques) only in Premium Pro tier
  • Desktop apps for Mac and Windows; iOS/Android support limited to specific integrations
  • Yearly subscriptions significantly more cost-effective than monthly (67% savings)

Pricing, plan by plan

Greasemonkey

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

ProWritingAid

Free
  • FreeFree
    • Basic grammar and spelling checks
    • 500-word limit per check
    • 2 report runs daily
  • Premium$30/month
    • Unlimited word count
    • Unlimited rephrases
    • 5 Sparks daily
  • Premium Pro$36/month
    • All Premium features
    • 50 Sparks daily
    • 3 Chapter Critiques daily

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 ProWritingAid if

  • You need grammar checking.
  • You want to start without paying.
  • You work on Web, Windows, Mac, Chrome, Firefox, Edge.
  • You also want style analysis.
ProWritingAid review

Questions people ask

Is Greasemonkey or ProWritingAid better?
Neither clearly leads. Greasemonkey starts at Free and ProWritingAid at Free, and user ratings are close enough to be indistinguishable. Choose on capability and platform support.
Which is cheaper, Greasemonkey or ProWritingAid?
Greasemonkey starts at Free and ProWritingAid at Free.
Does Greasemonkey or ProWritingAid run on more platforms?
Greasemonkey runs on Firefox. ProWritingAid runs on Web, Windows, Mac, Chrome, Firefox, Edge.
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 ProWritingAid is typically brought in for.
What can Greasemonkey do that ProWritingAid cannot?
Greasemonkey covers Userscript execution, Built-in script editor, GM. API, @resource support. ProWritingAid covers Grammar checking, Style analysis, Readability reports, Plagiarism checker.

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
ProWritingAid: How much does ProWritingAid cost?

ProWritingAid is free. Premium plan costs $30/month ($120/year), and Premium Pro costs $36/month ($144/year). Both yearly plans offer significant monthly savings. Lifetime options cost $399 (Premium) or $699 (Premium Pro).

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
ProWritingAid: Is there a free version of ProWritingAid?

Yes. The free plan includes basic grammar and spelling checks with a 500-word limit per check, 2 report runs daily, 10 rephrases daily, and 3 Sparks daily.

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
ProWritingAid: What is the difference between Premium and Premium Pro?

Premium ($30/month) includes 25+ analysis reports and 1 Chapter Critique daily. Premium Pro ($36/month) adds 50 Sparks daily, 3 Chapter Critiques daily, live workshops, and group critique sessions.

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
ProWritingAid: Does ProWritingAid offer a refund guarantee?

ProWritingAid offers a 3-day money-back guarantee for yearly and lifetime subscriptions. Monthly plans have no refund option.

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
Share

Related pages

More on Greasemonkey

More on ProWritingAid

Keep looking

Other head to heads