Grammarly suits business owners and teams who want clean, on-tone writing wherever they type, with AI prompts built in. ProWritingAid suits authors and long-form writers who want deep line-editing reports and story tools. Both have free plans, but ProWritingAid's free reports are capped at 2 runs a day on 500 words, which matters if you edit long documents.
Grammarly and ProWritingAid both catch spelling and grammar slips, so the useful question is what else you need. Grammarly leans towards everyday business writing and AI help across every app. ProWritingAid leans towards manuscripts, with reports and critiques built for novelists and long-form writers.
Grammarly and ProWritingAid feature by feature
| Grammarly | ProWritingAid | |
|---|---|---|
| Free plan | Yes, a Free plan | Yes, a free tier |
| Spelling and grammar | Yes, on free | Yes, on free |
| Tone | See your tone on free; adjust it on Pro | Not a headline feature |
| AI writing help | 100 AI prompts a month on free; 2,000 per member on Pro | Rephrases: 10 a day on free, unlimited on Premium |
| Deeper editing | Full-sentence rewrites and fluency help on Pro | 25+ writing analysis reports on Premium |
| Plagiarism and AI detection | On Pro | Not listed on the plans page |
| Fiction tools | Not a focus | Story Canvas, plot and character analysis, chapter critique |
| Where it works | Docs, desktop, mobile and browser | Not detailed on the plans page |
| Teams | Enterprise with data loss prevention and BYOK encryption | Comment and share documents on Premium |
Grammarly's angle on writing
Grammarly's plans page keeps the free tier simple: write without spelling and grammar mistakes, see your writing tone, and generate text with 100 AI prompts a month. Pro adds full-sentence rewrites, tone adjustment, help writing fluently in English, plagiarism and AI-text detection, and 2,000 prompts per member. It's designed to follow you into email, documents and the browser.
- Tone feedback before an email goes out.
- Fluency help for writing in English.
- Enterprise security such as data loss prevention.
ProWritingAid's angle on writing
ProWritingAid's plans page reads like it was written for authors. The free plan includes grammar, spelling and punctuation, a Word Explorer and thesaurus, more than 40 document types, writing session tracking and a few runs of Story Canvas idea feedback. Premium unlocks unlimited line-editing reports and rephrases, a custom style guide, author comparison and chapter critiques.
- Reports on readability, overused words and sentence structure.
- Plot, character and manuscript analysis for fiction.
- Monthly, yearly and lifetime plan options.
Privacy and team controls
If you're rolling a writing tool out to staff, the plans pages point in different directions. Grammarly's Enterprise plan, available through Superhuman Go, lists data loss prevention, BYOK encryption, custom roles, SAML single sign-on and audit logs. ProWritingAid lists 100% data security and privacy among its plan features and adds commenting and document sharing on Premium. A business with client confidentiality rules will want to read Grammarly's security list closely; a solo author probably won't need it.
How the free limits feel in practice
ProWritingAid is specific about its free plan: each line-editing report can run up to 2 times a day on 500 words of text, with 10 Rephrases and 3 Creative Nudges a day. That's fine for a blog intro and frustrating for a long report or a book chapter. Grammarly's free plan doesn't put a word cap on spelling and grammar checks on the plans page, but its AI help is rationed at 100 prompts a month. Decide whether you need checking or rewriting, because the free plans ration different things.
Business writing or books
If your writing is emails, proposals, social posts and web copy, Grammarly fits the way you already work, because it checks in the apps you type in. If you're writing a book, a long course or a lengthy guide, ProWritingAid's reports and critiques are aimed at that job. For more options built around business writing, see my roundup of AI-assisted writing tools for small business owners.
Whichever you use, AI rewrites can flatten your voice. My guide on stopping AI writing sounding like AI explains what to look for.
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My advice on Grammarly or ProWritingAid
Run the same piece through both free plans: one email and one long article. If the email is where you felt the difference, choose Grammarly. If the long article is where one tool taught you something about your writing, that's ProWritingAid. Accept suggestions one at a time, though; neither tool knows your audience the way you do.
Do you make a writing or grammar tool? Tool makers can ask to be considered for a featured place in comparisons like this one.
Frequently asked questions
Is Grammarly free?
Yes. Grammarly's free plan checks spelling and grammar, shows your writing tone and includes 100 AI prompts a month.
Is ProWritingAid free?
Yes. Its free plan includes grammar, spelling and punctuation checks, a thesaurus, 40+ document types, and line-editing reports limited to 2 runs a day on 500 words.
Which one is built for novelists?
ProWritingAid. Its plans page lists Story Canvas, plot and character analysis, chapter critique and manuscript analysis.
Does Grammarly check for plagiarism?
Yes, on the Pro plan, which also detects AI-generated text.
