Grammarly vs ProWritingAid
Grammarly is an everyday writing assistant that follows you across apps; ProWritingAid is built for long-form writers, with detailed reports and story critiques. Their AI training policies differ sharply.
Key differences
- Focus: Grammarly covers emails, docs and messages anywhere you type; ProWritingAid focuses on manuscripts, blogs and long documents.
- Price: Grammarly Pro is listed at $12/month; ProWritingAid Premium is $10/month billed yearly ($30 monthly), with a $399 lifetime option.
- AI training: Grammarly's policy says it trains AI on collected information unless you turn off the training control; ProWritingAid promises never to use your writing to train its algorithms.
- Free plan: both have one, with ProWritingAid's limited to a few report runs.
- Platforms: Grammarly has mobile keyboard apps; ProWritingAid centers on web and desktop.
Side by side
| Grammarly | ProWritingAid | |
|---|---|---|
| Free plan | Yes: free plan with spelling and grammar fixes, tone detection and 100 AI prompts. | Free plan with Story Canvas, writing sessions and limited reports. |
| Pricing | Pro $12/month on the plans page (billing period not shown there); free trial available. Check terms at checkout. | Premium $10/month billed yearly ($120/year) or $30 monthly; Premium Pro $12/month yearly or $36 monthly; Lifetime Premium $399 one-time. |
| Platforms | iOS, Android, Web, Mac, Windows | Web, Mac, Windows |
| AI features | AI writing assistant and prompts; Full-sentence rewrites and tone adjustments; AI agents | Rephrase and Sparks AI suggestions; Chapter Critique AI story feedback; Line-editing reports |
| Used to train AI? | Possibly. The privacy policy says Superhuman (Grammarly) uses collected information to train its AI models, and you can turn off training on your content with a control in account settings. | No. ProWritingAid's Responsible AI page says, "We will never use your writing to train our algorithms." |
| Privacy | Grammarly is now part of Superhuman Platform Inc.; Says it makes money from paid plans, not by selling user content; Shares cookie and ID data with ad partners, which may count as "sharing" under some privacy laws; Privacy policy effective July 6, 2026 | Responsible AI page promises it will never use your writing to train its algorithms; Says it only uses your text to help you improve your writing |
| Best for | Anyone who writes daily and wants AI help with clarity and tone. | Writers working on books, blogs or long documents who want detailed editing reports. |
| Last verified | Oct 16, 2026 | Oct 16, 2026 |
We don't declare a winner: the right choice depends on budget, platform and how you feel about AI processing your data. All facts link to sources on each app's page.