Reviewed 14 October 2026 against Grammarly, QuillBot, DeepL and Anthropic documentation. HumanRank has not yet run a blind editing test of these tools, so this guide gives no measured ranking.
Short answer
Grammarly is the most practical default for ongoing editing: its free plan includes tone detection and 100 AI prompts a month, with extensions for four major browsers. Use Claude when you need to rework a long draft. QuillBot is the better fit for paraphrasing a passage, and DeepL Write for polishing text in German, French, Italian, Spanish, Portuguese or English. Check training settings first, because three of the four train on individual users' text by default.
Decision table
| Need | Tool | Documented fact that matters | Main limitation | HumanRank score |
|---|---|---|---|---|
| Everyday editing everywhere | Grammarly | Free plan: 100 AI prompts a month and tone detection | Individual accounts are used for training by default | Not tested |
| Revising a long draft | Claude | Consumer users choose whether chats train models | A general assistant, not an inline editor | Not tested |
| Rephrasing a passage | QuillBot | 9 predefined paraphrase modes plus custom modes | Free users get only Standard and Fluency | Not tested |
| Polishing in European languages | DeepL Write | Business, Academic and Casual styles, plus tones | Free version texts are used for training | Not tested |
The four tools on the same fields
Grammarly
- Best for: catching errors and adjusting tone across email, documents and the browser.
- Documented strength: Grammarly's plans page lists 100 AI prompts a month and tone detection on Free. Pro adds full-sentence rewrites, tone adjustment and 2,000 prompts. Desktop apps cover Windows and Mac, and extensions cover Chrome, Safari, Firefox and Edge.
- Main limitation: Grammarly says product improvement and training is on by default for individual users (support article). It is off by default for Education accounts and for business plans bought through Grammarly's sales team. Team accounts bought on Grammarly's website start with it on until an admin turns it off.
Claude
- Best for: restructuring an argument, tightening a long piece or drafting from detailed notes.
- Documented strength: Claude works on whole documents rather than single sentences. It has desktop apps for macOS and Windows, a Chrome extension and a Microsoft 365 integration.
- Training control: Anthropic's consumer terms update lets Free, Pro and Max users choose whether their chats are used for training. If you allow it, data is kept for five years. If not, the existing 30-day retention applies. Team, Enterprise and API use are outside these consumer terms.
- Main limitation: a chat assistant does not sit inside every text box the way an editor does, so it suits substantial revision more than quick fixes.
QuillBot
- Best for: rewording a paragraph while you control how far it moves from the original.
- Documented strength: QuillBot's paraphrasing tool offers 9 predefined modes plus custom modes, a synonym slider and rephrasing in more than 20 languages. It is available as Chrome, Edge and Safari extensions, Windows and macOS apps, a Word add-in, and mobile apps.
- Main limitation: free users get only the Standard and Fluency modes. QuillBot uses inputs for training by default, with an opt-out in the extension settings, and says it never trains on Team Plan text (trust center).
DeepL Write
- Best for: polishing text in a supported European language, where register and tone matter.
- Documented strength: DeepL Write corrects spelling, grammar and punctuation, offers Business, Academic and Casual styles, and tones such as Friendly and Diplomatic. Write Pro supports German, French, Italian, Spanish, Portuguese and English.
- Main limitation: DeepL's privacy policy says free-version content is processed for a limited time to train its networks. The same policy says the free version may not be used to improve text containing personal data of any kind; a Pro subscription is required for that use. Write Pro texts are not stored permanently.
Choose by how much rewriting you need
The right tool depends on how far the text must move:
- Fix errors, keep the words: Grammarly or DeepL Write.
- Reword a passage: QuillBot, with the mode set as conservatively as the task allows.
- Restructure the piece: Claude, working from the full draft and your notes.
Every rewrite can drop a qualification, a number or a citation. Compare the output against the original line by line before you accept it.
A note on AI detectors
A detector score is not proof of how a text was written.
Writers who use these tools often worry about AI detection. Peer-reviewed research gives reason for caution about the detectors themselves. Liang and colleagues found that GPT detectors consistently misclassify non-native English writing samples as AI-generated, while native writing samples were identified accurately (Patterns, 2023). Treat a detector result as one signal, never as proof on its own.
How to test a writing tool
- Use three real pieces: a short email, an article opening and a technical paragraph with a number, a date and a citation.
- Run each through two tools with comparable settings.
- Count changes that need repair, such as altered meaning, lost hedges and new errors, not just changes made.
- Check that your intended voice survived. A smoother sentence that says something different is a failure.
Related categories
More categories in the HumanRank category index: best AI chatbots, best AI search tools and best AI coding tools.
Method and limits
- How we rank and how we are funded: our ranking method explains what a future HumanRank test will measure, and our disclosure explains which links may earn money.
- Sources: vendor plan, product, privacy and help pages read on 14 October 2026, plus one peer-reviewed study.
- Not tested: HumanRank has not yet measured edit accuracy, meaning preservation or speed. Scores read "Not tested" until a published test exists.
- Not published: QuillBot's free word limit and DeepL Write's free character limit. Neither appeared on a vendor page we could open.
- Prices: we left them out, because one plan page did not state a billing period clearly.
Frequently asked questions
What is the best AI writing tool? No tool has a measured win on HumanRank yet. Grammarly suits everyday editing, Claude suits deep revision, QuillBot suits paraphrasing, and DeepL Write suits European-language polish.
Does Grammarly use my writing to train its AI? For individual users it does by default, and you can opt out. Education and sales-team plans start with training off, while website-purchased team plans start with it on.
How many paraphrasing modes does QuillBot have? QuillBot lists 9 predefined modes plus custom modes. Free users can use Standard and Fluency.
Which languages does DeepL Write support? Write Pro supports German, French, Italian, Spanish, Portuguese and English.
Is Claude a grammar checker? Not primarily. It works best on larger revisions. For inline error checking, a dedicated editor such as Grammarly fits better.
Can AI detectors tell if I used a writing tool? Not reliably. Peer-reviewed research shows detectors misclassify non-native English writing as AI-generated.
Does DeepL keep my text? Free-version text is processed for a limited time to train DeepL's networks. The same policy says the free version may not be used to improve text containing personal data of any kind; a Pro subscription is required for that use. Write Pro texts are not stored permanently.
Which writing tool works in Microsoft Word? QuillBot has a Word add-in, and Claude offers a Microsoft 365 integration.