Grammarly, QuillBot and ProWritingAid are often shortlisted together because all three promise better writing. In practice they have drifted toward different jobs: Grammarly toward an AI writing assistant that works inside many apps, QuillBot toward paraphrasing and related text tools, and ProWritingAid toward in-depth reports and, increasingly, fiction writing support.
This article is a decision framework plus researched facts about each product. It is not a ranking and it names no winner.
How we researched this: we did not run hands-on tests for this article. It is based on the vendor’s own documentation and public sources, checked on 11 November 2026. Features and prices change, so confirm details on the vendor’s site before you buy.
Key takeaways
- Grammarly’s plans page lists Free, Pro and Enterprise, with AI prompt allowances (100 a month on Free, 2,000 per member a month on Pro). It also says moving from Premium to Pro cancels Premium, so old plan names may appear in older reviews.
- QuillBot’s plans page centres on paraphrasing modes, with a Free plan capped at 125 words per paraphrase and a Premium plan with unlimited paraphrasing in 9 modes.
- ProWritingAid’s pricing page now lists story-focused features such as Story Canvas, Chapter Critique and Story Credits, next to its grammar and style reports.
- Data policies differ. ProWritingAid says your writing is not used to train its AI models. Grammarly offers an opt-out of training. QuillBot says inputs are used for training to improve its services, with opt-outs and an exception for Team plans.
- AI detector and humaniser tools inside writing apps are not proof of anything. Check the rules of your school or employer, and test on your own writing.
Why compare these
Writing assistants check grammar, suggest rewrites and, in newer versions, generate or reshape text with AI. People use them for email, reports, essays, blog posts and manuscripts. Because the categories blur, a fair comparison starts from your writing task rather than from a feature list. If you write for a brand, our guides to building a brand voice guide that AI can follow and writing newsletters with AI without losing your voice are good companions.
What has changed in how they present themselves
Grammarly’s AI writing assistance page lists four AI agents: Resume Builder, Citation Finder, AI Grader and Reader Reactions. It says it rewrites text for tone, length and formality, generates ideas and outlines from prompts, and lets admins set brand tones. It describes working across more than a million apps and websites.
ProWritingAid’s pricing page lists features such as Story Canvas Idea Feedback, Chapter Critique, Creative Nudges and Sparks, plus live workshops and a Story Credits system sold separately. That tells you the product is aimed more and more at people writing stories, though its help centre still describes grammar checks and 25+ writing reports.
QuillBot’s premium page highlights paraphrasing in modes, a humaniser, an AI detector and summaries alongside grammar and plagiarism checks.
Quick overview table
| Item | Grammarly | QuillBot | ProWritingAid |
|---|---|---|---|
| Headline job | AI writing assistant with grammar, rewriting and agents | Paraphraser with grammar, summaries, detector and humaniser | Style and grammar reports plus story-focused tools |
| Plans (official pages) | Free, Pro, Enterprise | Free, Premium, Team | Free, Premium, Premium Pro |
| Lifetime option | Not listed | Not listed | Yes, on Premium and Premium Pro |
| Languages stated | Not confirmed from pages we read | 25+ languages for the Paraphraser, including four English variants | Not confirmed from pages we read |
| Where it works | Google Docs, Word, Gmail, Outlook, Slack and more | Web app and browser extensions (Edge extension page exists) | Desktop, browser, web editor; Google Docs, Word, Scrivener |
| Training on your text | Opt-out available | Used for improvement; opt-outs; Team plan excluded | States it is not used for AI training |
Criteria that matter
Follow a consistent method, as in how to compare AI tools side by side fairly.
- Your writing type: business email, academic prose, marketing copy or fiction.
- Where you write: in a browser, Google Docs, Word, Scrivener or email.
- Correction versus rewriting: do you want fixes, or full rewrites and generation?
- Your language: check the languages you write in by testing real text.
- Data handling: especially for confidential or unpublished work.
- Cost model: monthly, annual or lifetime, and AI usage limits.
Documented features
Grammarly
The plans page lists on Free basic spelling and grammar checks, a tone view and 100 AI prompts a month. Pro adds tone adjustment, full-sentence rewrites, fluent English writing, inclusive language, citation consistency, AI-text and plagiarism detection, and 2,000 AI prompts per member per month, plus team features such as a style guide, brand tone, Knowledge Share, Snippets and analytics. Enterprise adds unlimited AI prompts, SSO, SCIM, managed mode, custom roles, data loss prevention and BYOK encryption.
QuillBot
The Free plan allows paraphrasing up to 125 words in 2 modes, basic grammar fixes, Basic-mode humanising, basic summaries and a limited AI Detector. Premium adds unlimited paraphrasing in 9 modes plus custom modes, advanced grammar and writing suggestions, tone insights, plagiarism prevention for 25,000 words a month, unlimited Advanced-mode humanising and AI Detector use, summaries up to 6,000 words, 100 MB of storage and faster processing. Team adds usage metrics, a user dashboard, centralised billing and data control.
ProWritingAid
The help centre says it gives real-time suggestions on style and readability, flags grammar, punctuation and spelling, includes a Rephrase tool, and offers 25+ reports such as sticky sentences, repetition and structure. The free tier gives basic suggestions on up to 500 words. Premium adds unlimited line editing and Rephrases, an Outline Crafter, a custom style guide, 25+ analysis reports, author comparison, sharing and comments. Premium Pro adds more daily critiques and nudges, live workshops, a 200+ workshop library, cowriting sprints and group critiques.
| Need | Grammarly | QuillBot | ProWritingAid |
|---|---|---|---|
| Tone adjustment | Pro | Tone insights on Premium | Rephrase tool; styles by report |
| Rewrite sentences | Full-sentence rewrites on Pro | Paraphrasing in 2 modes (Free) or 9 modes (Premium) | Rephrase; unlimited on Premium |
| Team style rules | Style guide and brand tone | Team plan dashboard | Custom style guide on Premium |
| Long-form critique | Not stated on pages we read | Not stated | Chapter Critique and Story Canvas |
Languages and where you can use each
QuillBot’s help centre says its Paraphraser works with more than 25 languages, including US, UK, Canadian and Australian English, Spanish, French, German, Chinese, Portuguese, Hindi and Japanese, and says to check the language menu inside the Paraphraser for the current list. It lists separate pages for other tools such as the Plagiarism Checker, so support may differ by tool.
For Grammarly and ProWritingAid we did not retrieve a language list, so test your language directly. Grammarly says it works across 1 million+ apps and websites including Google Docs, Microsoft Word, Gmail, Outlook, Slack, Salesforce, LinkedIn, Microsoft Teams, Google Sheets, Zendesk and Jira. ProWritingAid works with Google Docs, Microsoft Word and Scrivener and offers desktop, browser and web editor options.
Plagiarism, AI detection and humanising
Grammarly Pro lists AI-text and plagiarism detection. QuillBot lists plagiarism prevention (25,000 words a month on Premium), a limited AI Detector on Free and an unlimited one on Premium, plus a humaniser. Be careful with these features. AI detectors give probabilities, not proof, and they can produce false positives and false negatives. A humaniser that rewrites text to avoid detection may breach an academic or workplace policy. Read the rules that apply to you, and see how to spot AI-generated text and images for a balanced view.
Use writing tools to improve text you are accountable for, and check any rewritten text for meaning changes. Our guide on how to check AI output for mistakes gives a method.
Pricing models
Prices below were read on each vendor’s page on 11 November 2026, in US dollars. Confirm on the vendor page, and see how to read an AI tool’s pricing page for traps.
| Vendor | Plan | Price as shown | Notes |
|---|---|---|---|
| Grammarly | Free | $0 | 100 AI prompts a month |
| Grammarly | Pro | $12 | The page does not say whether this is monthly or annual; free trial available |
| Grammarly | Enterprise | Contact sales | Unlimited AI prompts, SSO, SCIM |
| QuillBot | Free | $0 | No credit card; 125 word paraphrase cap |
| QuillBot | Premium | $5.00 a month, or $8.33 a month billed annually, as shown | The two figures look unusual in that order, so confirm which applies; 3-day money-back for new users |
| QuillBot | Team | Custom | Discounted single invoice for teams of 5 or more |
| ProWritingAid | Premium | $30 monthly; $10 a month billed yearly at $120; $399 lifetime | Monthly plans not refundable |
| ProWritingAid | Premium Pro | $36 monthly; $12 a month billed yearly at $144; $699 lifetime | Story Credits sold separately |
Other details from the pages: ProWritingAid yearly and lifetime plans include a 3-day money-back guarantee, Story Credits are nonrefundable, students can get 25% off yearly plans through Student Beans, and K-12 schools can access premium features free through its education programme. QuillBot Premium can be paused, used on up to 10 devices at once, and paid by card or PayPal. Grammarly’s page says an email reminder arrives 2 days before a free trial ends.
Compare by what you will use: a lifetime licence suits long-term use of one tool, but check what “lifetime” means in the vendor’s help centre, and remember product features change.
Privacy and data
This is where the stated policies differ most. Your drafts may include client information, unpublished manuscripts or personal data. See how to protect company data when using AI tools for a checklist.
| Topic | Grammarly (trust page) | QuillBot (trust centre) | ProWritingAid (help centre) |
|---|---|---|---|
| Training on your text | You can opt out via “Product Improvement and Training” in account settings | Inputs and usage data used to improve services; Team plan text not used; opt-outs in extension v4.37.0 or later | States your writing is not used to train its AI models |
| Storage | Saved documents kept until you delete them or your account | Text storage on by default, can be disabled; retention periods not stated | Text for analysis deleted after reports, usually within seconds; Web Editor documents stored encrypted |
| Security claims | Annual security certifications; third-party penetration testing | EU-U.S. and Swiss-U.S. Data Privacy Frameworks, CASA Tier 2, GDPR, CCPA, PCI DSS | SOC 2 Security, AES-256 at rest, TLS 1.2 or higher |
| Sale of data | Not stated on the page we read | States it does not sell user data | States data is not sold or transferred, with listed exceptions |
These are vendor statements, so confirm them in current policies and account settings. If your work is confidential, check which setting is on by default and whether the plan you use changes it, for example QuillBot’s Team exclusion or Grammarly’s opt-out.
Who each suits
| If you need | Documented fit |
|---|---|
| Writing help inside email, documents and chat across many apps | Grammarly lists a wide range of apps and team style controls |
| Paraphrasing in several modes, summaries and a detector in one place | QuillBot documents 9 paraphrase modes on Premium and 25+ languages for the Paraphraser |
| Detailed reports for long-form and fiction, with a lifetime option | ProWritingAid documents 25+ reports, story tools and lifetime plans |
| A firm no-training statement for your writing | ProWritingAid states this; check the others’ opt-outs |
| Enterprise controls | Grammarly lists SSO, SCIM, DLP and BYOK encryption on Enterprise |
This is “best for X if Y” from documented features, not a score. A student, a marketing team and a novelist have different needs, and each should test with their own writing.
How to run your own test
- Pick three samples of your own writing: a short email, a 500 word article section and a hard paragraph you know is awkward.
- Run each through the free plan or trial of every tool.
- Accept or reject each suggestion and count: how many fixed real errors, how many changed your meaning, how many were style preferences you disagree with?
- Test the rewrite features on one paragraph and compare the result against your original for meaning and voice.
- If you write in another language, test that language specifically.
- Read the data settings and the plan terms before pasting confidential text.
See how to test an AI tool before you pay for it for the general method.
Decision checklist
- Which apps do you write in, and does the tool work there?
- Do you need corrections, rewrites, or story-level critique?
- Does it support your language, tested on real text?
- Have you found and set the training and storage options?
- Are AI prompt limits enough for your use?
- Do you know whether the price you see is monthly or annual?
- Would a lifetime plan make sense, and what does lifetime mean for that vendor?
- Does your school or employer allow detector or humaniser features?
Frequently asked questions
Which one is best for grammar?
We do not rank them. All three list grammar checking on free tiers, and the quality for your writing is something to test with your own samples.
Is QuillBot only a paraphraser?
No. Its plans page also lists grammar, summaries, plagiarism prevention, an AI Detector and a humaniser, but paraphrasing remains the centrepiece.
Does ProWritingAid train on my writing?
Its help centre says your data and writing are not used to train its AI models or algorithms.
Can I turn off training in Grammarly?
Its trust page says you can opt out in account settings under “Product Improvement and Training”.
Are AI detectors reliable?
They estimate likelihood and are not proof. Do not rely on a single score to judge someone’s work.
Is a lifetime licence worth it?
Only ProWritingAid lists one on the pages we read. It depends on how long you will use it, so read the vendor’s explanation of what lifetime means first.
Conclusion
Grammarly, QuillBot and ProWritingAid overlap on basic corrections but now serve different needs: an AI assistant across apps, a paraphrasing toolkit, and a report-driven editor with story tools. Decide by your writing type, your apps, your language and your data rules, then test with your own samples. Start with how to compare AI tools side by side fairly and re-check pricing pages on the day you buy.
Sources
- Grammarly: plans, accessed 11 November 2026
- Grammarly: AI writing assistance, accessed 11 November 2026
- Grammarly: User Trust Center, accessed 11 November 2026
- QuillBot: Premium and plans, accessed 11 November 2026
- QuillBot: Trust Center, accessed 11 November 2026
- QuillBot help: Paraphraser languages, accessed 11 November 2026
- ProWritingAid: pricing, accessed 11 November 2026
- ProWritingAid help: what it does, accessed 11 November 2026
- ProWritingAid help: is my data safe, accessed 11 November 2026
