Compute desk
AI writing tools comparison: what each one actually does
Four writing assistants, set side by side using only their makers' help and plan pages. No ratings, no prices: just what each one does, where it runs and what it asks of you in access.
An AI writing tools comparison comes down to access, not ability. Copilot in Word, Gemini in Google Docs, Grammarly and Apple's Writing Tools all generate and rewrite text. They differ in which plan, device or region unlocks them. None of the vendors publishes an accuracy figure on these pages, and Microsoft tells users to review the result.
Key takeaways
- Copilot in Word and Gemini in Docs both draft from a prompt, rewrite selected text and summarize documents.
- Copilot needs an eligible Microsoft 365 subscription or Copilot license; Gemini in Docs needs an eligible Google Workspace or Google AI plan.
- Grammarly's Free plan includes a small monthly allowance of generative-AI prompts.
- Apple's Writing Tools depend on Apple Intelligence, which is not available in all languages or regions.
- None of the pages publishes an error rate for generated text.
If you are choosing a writing assistant for papers, grant drafts or lab notes, this AI writing tools comparison sets four vendors' own pages side by side. You will see what each tool does and what it costs you in access: the plan, device or program it needs. It comes from our AI desk, and every claim below links to the page it came from.
What do AI writing tools do?
The tools built into everyday software do three jobs: draft from a prompt, rewrite what you have, and summarize.
Microsoft's help page for Copilot in Word sorts these into three verbs. "Create" starts a draft from a prompt, outline, notes or a referenced file. "Refine" rewrites selected text, adjusts tone or makes content more concise. "Comprehend" summarizes a document, answers questions about it or pressure-tests ideas [1].
Google's page for Gemini in Docs describes the same ground with different buttons. You can edit with a prompt, or highlight text and use quick actions: Rephrase, Shorten, Elaborate, Bulletize or Summarize, plus More formal and More casual [2]. It can also draw on your Drive, Chat and Gmail files and the web [2].
Apple's Writing Tools on the Mac offer Rewrite (with Friendly, Professional or Concise tones), Proofread, and Summarize or Key Points [4]. Grammarly's plans page lists text generation with AI prompts on every plan, and full-sentence rewrites on its paid tiers [3].
For a scientist, the useful distinction is not which tool writes "better," which no page here measures. It is where the tool lives, what it can read and what switches it on.
How do the main AI writing tools compare?
The table below uses only what each vendor documents on the page cited. It is a set of facts, not a ranking.
| Tool | Where it runs | What it does, per its page | Who can use it | Source page |
|---|---|---|---|---|
| Copilot in Word | Word for Microsoft 365, Word for Mac, Word for iPad, Word for the web | Drafts from a prompt, outline, notes or file; rewrites, adjusts tone, shortens; summarizes and answers questions | Users with an eligible Microsoft 365 subscription or Microsoft Copilot license; may depend on organization settings | Microsoft Support |
| Gemini in Google Docs | Google Docs on a computer | Edits with a prompt; Rephrase, Shorten, Elaborate, Bulletize, Summarize; formal or casual tone; uses your files as sources | Users on an eligible Google Workspace or Google AI plan; some features via Workspace Experiments | Google Docs Editors Help |
| Grammarly | Desktop apps, browser extensions, Microsoft Office, Google Docs, mobile | Generates text with AI prompts; tone feedback; full-sentence rewrites on paid plans | Free plan (100 AI prompts a month); Pro (2,000 prompts per member a month); Enterprise (unlimited prompts per member a month) | Grammarly plans page |
| Apple Writing Tools | Most places you write on a Mac, including third-party apps and websites, per Apple | Rewrite in set tones, Proofread, Summarize or Key Points; optional ChatGPT extension to compose | Requires Apple Intelligence, which is not available in all languages or regions; usage limits may apply | Apple Support |
Copilot in Word
Microsoft says Copilot in Word is "available to users with an eligible Microsoft 365 subscription or Microsoft Copilot license" [1]. The page applies to Word for Microsoft 365, Word for Microsoft 365 for Mac and Word for iPad, and points to a web version too [1]. Availability may also depend on your organization's settings [1], which matters at an institute where IT decides what is enabled.
After Copilot generates content, review the result. You can keep it, discard it, or continue refining it with a follow-up prompt.
Grammarly
Grammarly's plans page names three plans: Free, Pro and Enterprise [3]. Free covers spelling and grammar, tone detection and text generation with 100 AI prompts a month [3]. Pro adds full-sentence rewrites, tone adjustment, plagiarism and AI-text detection, and 2,000 prompts per member per month [3]. Enterprise lists unlimited prompts per member per month and is, per the page, available through Superhuman Go [3].
Apple's Writing Tools
Writing Tools run with Apple Intelligence, which Apple says on macOS 27 "is not available in all languages or regions" [4].
Are there AI writing tools like ChatGPT that run inside Google Docs?
Yes. Google's help page describes Gemini working inside the document. You click Gemini, type a prompt, and it can target one section ("Add evidence to my Research section") or the whole file [2].
Three documented details shape how it behaves.
You need an eligible plan
The page states plainly: "This feature requires an eligible Google Workspace or Google AI plan" [2]. It does not list which plans qualify on that page; it links out to Google's getting-started guide [2].
Some features are experiments
Matching the writing style of another document is available through Google Workspace Experiments, which Google describes as "a trusted tester program for personal accounts to try new AI features" [2]. Treat anything in that program as a trial feature, not a fixture.
It suggests; you decide
Gemini shows its changes as suggestions you accept one at a time, accept all or reject all [2]: the same review loop as tracked changes.
If you want a ChatGPT-style assistant outside Google's suite, Apple's Writing Tools on the Mac include a ChatGPT extension. Apple says it is available only where the ChatGPT app and service are available, and that you choose what content to send [4].
Can you use AI writing tools free online?
Partly, and only within the limits the vendors publish.
Grammarly's Free plan is the clearest documented free option here, with 100 AI prompts a month [3]. Gemini in Docs requires an eligible Google Workspace or Google AI plan [2]. Copilot in Word needs an eligible Microsoft 365 subscription or Copilot license [1]. Apple's Writing Tools need Apple Intelligence, and usage limits may apply [4].
None is "free online" in the sense of a website with no account. For more on how we handle sources and corrections, see about us, and for the rest of our coverage, the blog.
Frequently asked questions
Does Copilot in Word work on a Mac or iPad?
Microsoft's help page says it applies to Word for Microsoft 365 for Mac and Word for iPad, as well as Word for Microsoft 365, and it points to a web version [1].
Can Gemini in Docs read my other files?
Yes, if you add them. Google says you can draft and refine using information from your files in Drive, Chat and Gmail, and from the web. You add files through Sources or by typing @ and selecting them [2].
What does Grammarly Pro add over Free?
Per Grammarly's plans page, Pro adds full-sentence rewrites, tone adjustment, plagiarism and AI-text detection, and raises the allowance to 2,000 AI prompts per member per month [3].
Does Apple send my text to ChatGPT?
Only if you use the ChatGPT extension. Apple says you choose what to send, and that your request plus limited data such as time zone, country, device type and language goes to ChatGPT [4].
Will these tools change my document without asking?
Gemini shows suggestions you accept or reject [2]. Microsoft says you can keep, discard or keep refining what Copilot generates [1].