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Browser Extensions · head to head

Mercury Reader vs ProWritingAid

M

Mercury Reader

Browser Extensions

Clear clutter from articles instantly

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: Mercury Reader mercury Reader's underlying engine (Postlight Parser) is free open source software licensed under Apache License 2.0, per the GitHub repository, with no paid tier; ProWritingAid free plan limited to 500 word count with only 2 report runs per day
  • They diverge on capability: Mercury Reader covers Content extraction, ProWritingAid covers Grammar checking.
  • Prices and features above were last checked on 30 August 2026.

Where they differ

Only the attributes on which Mercury Reader and ProWritingAid actually diverge.

Attributes where Mercury Reader and ProWritingAid differ
AttributeMercury ReaderProWritingAid
Pricing modelfreefreemium
PlatformsChrome, Firefox, EdgeWeb, Windows, Mac, Chrome, Firefox, Edge
Founded20152013

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 Mercury Reader

  • Content extraction
  • Clean reading view
  • Custom themes
  • Font customization

Only in ProWritingAid

  • Grammar checking
  • Style analysis
  • Readability reports
  • Plagiarism checker
  • Safari support

Both cover

  • Chrome support
  • Firefox support
  • Edge support

What people use each for

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

Mercury Reader

No use cases recorded yet. See the Mercury Reader review.

ProWritingAid

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

Where each one falls short

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

Mercury Reader

  • Mercury Reader's underlying engine (Postlight Parser) is free open source software licensed under Apache License 2.0, per the GitHub repository, with no paid tier

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

Mercury Reader

Free
  • FreeFree
    • Clutter removal
    • Clean reading
    • Custom themes

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 Mercury Reader if

  • You need content extraction.
  • You want to start without paying.
  • You work on Chrome, Firefox, Edge.
  • You also want clean reading view.
Mercury Reader 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 Mercury Reader or ProWritingAid better?
Neither clearly leads. Mercury Reader 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, Mercury Reader or ProWritingAid?
Mercury Reader starts at Free and ProWritingAid at Free.
Does Mercury Reader or ProWritingAid run on more platforms?
Mercury Reader runs on Chrome, Firefox, Edge. ProWritingAid runs on Web, Windows, Mac, Chrome, Firefox, Edge.
Can I use Mercury Reader for free?
Both have a free tier, so you can try either at no cost before committing.
What can Mercury Reader do that ProWritingAid cannot?
Mercury Reader covers Content extraction, Clean reading view, Custom themes, Font customization. ProWritingAid covers Grammar checking, Style analysis, Readability reports, Plagiarism checker. Both handle Chrome support, Firefox support, Edge support.

Answered from the vendors’ own pages

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
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
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
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
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