Best AI writing assistants in 2026: ChatGPT, Claude, Gemini in Docs, Copilot in Word and Grammarly

An AI writing assistant helps you get from a blank page to a finished draft: it can outline, write a first version, rewrite a paragraph for a different reader, tighten your wording and catch mistakes. In 2026 they come in three forms: general assistants such as ChatGPT and Claude, AI built into the editor you already use (Copilot in Word, Gemini in Google Docs), and tools that follow you everywhere you type, such as Grammarly and Apple’s Writing Tools. This guide compares the main options, what they cost in the US as of October 2026 and where each one fits, based on the vendors’ own help and pricing pages. We have not run a side-by-side writing test.

Best AI writing assistants at a glance

What an AI writing assistant can do

• Draft: turn notes, an outline or a few lines of instruction into a first version.
• Rewrite: change tone, length or audience without changing the meaning.
• Edit: tighten wording, fix grammar and flag unclear or inconsistent terms.
• Summarise: pull the key points out of a long document before you edit it.
• Use your sources: draw on other files, email or the web to fill in facts.

The main difference between products is where the help lives and how much control you keep over the changes. Tools built into an editor can show suggestions you accept or reject, while chat assistants hand you text to paste.

ChatGPT

ChatGPT is the most widely used general assistant and works well for first drafts, rewrites and brainstorming in its own app. Two features make it more useful for regular writing:

• ChatGPT for Word: an add-in, available on all ChatGPT plans including Free, that works in a sidebar next to your document. OpenAI suggests using it to draft a memo or report from notes, write an executive summary, revise a section for a different audience or find inconsistent terminology. Word uses token-based pricing at API rates and draws on your plan’s shared usage allowance. Your normal chats, memory and skills don’t carry over to the add-in. Our ChatGPT for Excel, Word and PowerPoint guide covers setup.
• Custom instructions and memory: you can tell ChatGPT once how you write and who you write for (up to 1,500 characters on Free and Go, 5,000 on paid plans above them), and memory carries preferences between chats. See ChatGPT memory explained.

On Pro, Business and Enterprise plans, ChatGPT Space adds shared pages that you and colleagues edit together with ChatGPT; our Space and Pages guide explains how they work. Plus costs $20 a month; see the ChatGPT profile for every plan.

Claude

Claude is a strong choice for long, careful writing work, and Anthropic’s add-in is built around keeping you in charge of edits. Claude for Word, available on Pro, Max, Team and Enterprise plans, can:

• Edit selected text while keeping the surrounding styles, numbering and formatting.
• Use tracked changes, so every edit lands as a revision you accept or reject in Word’s review pane.
• Work through comment threads, editing the text each comment points to and replying with what it changed.
• Fill templates in your document’s own heading and paragraph styles.
• Answer questions about the document with clickable citations to the right section.

It runs in Word on the web, Windows and Mac, and you can set persistent instructions such as “use formal tone” that apply to every Word conversation. Anthropic notes that add-in chat history is stored locally in your browser rather than on its servers.

In the Claude app itself, the free plan includes Claude Docs, living documents you write with Claude, and you can shape Claude’s voice with account-wide instructions or skills, which Anthropic says can apply “communication patterns based on your own writing.” Pro costs $20 a month or $17 a month billed annually, and Max starts at $100. Our Claude Design, Slides and Docs guide and beginner’s guide to Claude go further.

Gemini in Google Docs

If you write in Google Docs, Gemini is already in the toolbar. According to Google’s Docs Editors Help, you can:

• Edit with a prompt, such as “Make the introduction more concise and professional,” and Gemini shows suggestions in the document to accept one by one or all at once.
• Refine with one click: select text and choose Rephrase, Shorten, Elaborate, More formal, More casual, Bulletize or Summarize.
• Use other files as sources, by adding them from Drive or typing @, so Gemini can add data, evidence and citations.
• Match a writing style from another Drive document. For personal accounts this is part of Workspace Experiments, Google’s trusted tester programme.

Google says this needs an eligible Google Workspace or Google AI plan. Its plans page lists Gemini in Docs with Google AI Pro ($19.99 a month) and Ultra (from $99.99); AI Plus ($4.99) lists Gemini in Gmail and Vids instead. The free Gemini app also includes Canvas for writing outside Docs. Our Google AI Plus vs Pro vs Ultra guide compares the plans, and the Gemini profile covers the app.

Copilot in Word

Microsoft’s assistant lives inside Word on Windows, Mac and iPad. Microsoft groups what it does into creating a draft from a prompt, outline, notes or file; refining selected text; and comprehending long documents through summaries and questions. Useful details from Microsoft’s support page:

• Open it from the Copilot button in the corner of a document; it starts in the chat pane with Edit mode on.
• In a shared document, Copilot shows a preview of its suggested changes in chat first, and nothing goes into the document until you approve it.
• Choose Chat only when you want answers without any changes to the file.
• A model selector lets you pick a reasoning level or a supported model provider, such as OpenAI or Claude.
• Copilot can draw on your files, emails and meetings, but it doesn’t connect to external tools.

At home, Copilot in Word comes with Microsoft 365 Personal ($9.99 a month), Family ($12.99, where only the subscription owner gets the AI features), Premium ($19.99) or Pro ($99.99). Companies use Microsoft 365 Copilot. Our Microsoft Copilot plans explained guide sets out the differences, and Copilot vs ChatGPT compares the two assistants.

Grammarly

Grammarly takes the opposite approach to a chat assistant: it checks your writing as you type, in the browser, on Windows and Mac, in Microsoft Office, in Google Docs and on mobile. Grammarly is now part of Superhuman, a suite that also includes Superhuman Mail and Superhuman Docs.

It suits students and professionals who mostly need their own writing polished rather than written for them.

Apple Writing Tools

On recent iPhones, iPads and Macs, Apple’s Writing Tools are part of Siri AI. Apple says you can write with Siri “virtually anywhere” you type: describe what you need for a draft from scratch, or describe a change to refine what you’ve written. Apple Intelligence also proofreads automatically as you type, including in most third-party apps, and in Mail and Messages Siri can reflect the tone and punctuation you usually use with each person. There is no fee, but server-based features have daily usage limits, and Apple says expanded access will cost extra in future. See how to use Siri AI for supported devices.

Which AI writing assistant should you choose?

• You write in Word: start with Copilot if your Microsoft 365 plan includes it; add ChatGPT or Claude for Word if you prefer their models.
• You write in Google Docs: Gemini, with Google AI Pro or a Workspace plan.
• You want edits you can review line by line: Claude for Word’s tracked changes, or Gemini’s accept and reject suggestions.
• You want a free starting point: ChatGPT or Claude in chat, or Grammarly Free for corrections.
• You mostly need proofreading everywhere: Grammarly, or Apple’s Writing Tools on Apple devices.

Whatever you choose, read every draft before it goes out. AI assistants can invent facts, figures and quotes, so check anything you didn’t supply yourself. For a broader comparison of the big three, see ChatGPT vs Claude vs Gemini, and for writing email specifically, see the best AI email assistants.