Grammarly or ProWritingAid: which is better for Substack?

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Grammarly vs ProWritingAid for Substack writers

Checked 2026-10-28 on the vendors' sites and Substack's help center · Independent, no affiliate relationship with either tool

The short answer: Pick Grammarly if you want quick, everywhere proofreading: its free browser extension checks spelling and grammar as you type on the web, and Pro (from $12/mo) adds full-sentence rewrites and tone adjustments. Pick ProWritingAid if you write long essays or serialized fiction and want deep style reports: Premium is $10/mo billed yearly ($120) or $30 monthly. Both browser extensions work on web pages, so either can check drafts in the Substack editor.

Side by side

	Grammarly	ProWritingAid
Best at	Fast proofreading and tone as you type, across email, social and web apps.	Deep line-editing reports (25+ on paid plans) for long-form and fiction.
Free plan	Spelling and grammar, tone detection and 100 AI prompts a month.	Grammar, spelling and punctuation; each report runs on 500 words at a time, twice a day; 10 Rephrases a day.
Paid plans	Pro from $12/mo, with a free trial. Enterprise via sales.	Premium $10/mo billed yearly ($120) or $30 monthly; Premium Pro $12/mo billed yearly ($144) or $36 monthly; lifetime options.
What paid adds	Full-sentence rewrites, tone adjustments, plagiarism and AI-text detection, 2,000 AI prompts a month.	Unlimited reports and Rephrases on any length, custom style guide, Chapter Critique; Premium Pro adds live workshops and community.
Works in the Substack editor	Yes, through its browser extensions, which work across web apps.	Yes, through its Chrome, Edge and Firefox extensions, which work on any web page.
Refunds and trials	Free trial on Pro, with an email reminder 2 days before it ends.	3-day money-back guarantee on yearly and lifetime plans; no refunds on monthly plans.

Start free with either

Most Substack writers only need a second pair of eyes for typos before hitting publish. Both free plans catch spelling and grammar. Grammarly's free extension does it as you type; ProWritingAid's free reports cap you at 500 words at a time, which is fine for a Note but tight for a full post.

Essays and fiction: reports beat rewrites

If your posts run long, ProWritingAid's reports on repetition, sentence length, pacing, dialogue tags and readability show patterns across a whole draft. That's more useful for a weekly essay or chapter than one-sentence fixes. Its fiction tools (Chapter Critique, Story Canvas) only matter if you publish stories.

Keep your voice

Grammarly Pro's full-sentence rewrites and tone adjustments can make every post sound the same. Readers subscribe for how you write, so accept suggestions one at a time and skip the ones that don't sound like you. The same goes for ProWritingAid's Rephrases.

How the costs compare

Paying monthly, Grammarly Pro starts at $12 against ProWritingAid Premium's $30. Paying yearly, ProWritingAid Premium works out to $10 a month ($120). Check Grammarly's checkout for its billing options, since its plans page shows the Pro price without a yearly total.

Our pick

For most Substack writers, start with Grammarly's free extension for everyday proofreading. Add ProWritingAid Premium (billed yearly) if you publish long essays or serialized fiction and want a deeper edit before each post. For other options, including the free Hemingway web editor and LanguageTool, see the Editing & Proofreading category.

Our verdicts

Grammarly: The free browser extension is worth installing. Pro's rewrites can flatten your voice, so accept suggestions selectively.
ProWritingAid: More thorough reports than Grammarly. Worth trying if you write long essays or serialized fiction.

Sources

Prices change; confirm on each vendor's site. See how we verify tools. More tools like these: Editing & Proofreading.