Grammarly vs ChatGPT: which AI writing tool should you use?

Short answer: pick Grammarly if you mainly want to polish what you write, right where you write it. It checks grammar, clarity and tone as you type in email, documents and the browser, and adds agents for proofreading, paraphrasing, citations, plagiarism and AI detection. Pick ChatGPT if you want an assistant that drafts, rewrites, researches and explains things from a prompt, and does far more than writing. Many people use both: ChatGPT to get a first draft down, Grammarly to edit it.

You can find both on Unloc: Grammarly and ChatGPT. This comparison is based on Grammarly's and OpenAI's official websites, pricing pages and help centres.

Quick verdict

What Grammarly is

Grammarly started as a grammar checker and now describes itself as an AI partner that helps turn your thoughts into writing that is "clear, credible, and impossible to ignore". Its core is still real-time writing feedback: spelling, grammar, punctuation, clarity, tone suggestions and one-click paragraph rewrites. Around that, Grammarly now offers a set of task-specific AI agents, including Proofreader, Paraphraser, Humanizer, Reader Reactions, Citation Finder, AI Grader, AI Detector and a Plagiarism Checker.

Grammarly is now part of Superhuman, the company that also makes Superhuman Mail and Go, an AI assistant that brings agents into the tools you already use. Grammarly's plans page says Enterprise customers get Grammarly through Superhuman Go. For most individual users, though, Grammarly is still the familiar green "G" that sits in the corner of your screen while you type.

What ChatGPT is

ChatGPT is OpenAI's AI assistant. OpenAI splits it into three modes: Chat for questions, learning and everyday help; ChatGPT Work, which can create and edit documents, slide decks, spreadsheets and other deliverables; and Codex for coding. Writing is one use among many. OpenAI says ChatGPT can turn rough notes and thoughts into clear, polished writing, and draft messages, notes, plans, stories and posts that you edit as your thinking develops.

ChatGPT also searches the web, runs deep research, creates images, holds voice conversations, reads uploaded files and remembers context across chats, depending on your plan. If you are comparing ChatGPT with other assistants, see our guides to Claude vs ChatGPT and Perplexity vs ChatGPT.

Editing and proofreading

This is where Grammarly is strongest, and the main reason people choose it. You write as normal and Grammarly underlines what needs attention: a misspelling, a missing comma, a confusing sentence or a tone that may land badly. You accept or ignore each suggestion, so you stay in control of every change and can see exactly what was fixed. Grammarly's Proofreader agent goes further on structure and phrasing, and Reader Reactions lets you pick a target reader, such as a teammate or a teacher, and see how your writing might land with them.

ChatGPT can proofread too, and it is good at it, but the workflow is different. You paste your text in, ask it to fix the grammar or tighten the writing, and it returns a new version. Unless you ask it to list or explain its changes, you have to compare the two versions yourself, and it may change more than you wanted, including your voice. For quick, precise corrections in text you have already written, Grammarly is usually faster and safer. For a heavy rewrite, ChatGPT gives you more room.

Drafting and rewriting

The balance flips when you need new words rather than better ones. ChatGPT is built to generate: outlines, first drafts, alternative headlines, a reply in a different tone, a summary of a long document or an explanation of a hard topic. You can keep refining in the same conversation, and on paid plans projects and memory help it keep your context.

Grammarly also writes. Its plans include generative AI prompts for drafting text, replies and rewrites, with a monthly prompt allowance that grows on higher plans, and its Paraphraser adapts text for a different audience, tone or style. But Grammarly's AI is tuned for helping with the piece in front of you, not for open-ended research or long brainstorming sessions. If drafting from a blank page is your main need, ChatGPT is the stronger tool. You can also compare ChatGPT with a marketing-focused writer in our ChatGPT vs Jasper guide.

Where each one works

Grammarly's biggest practical advantage is that it comes to you. Its browser extension and desktop app work across a very large number of sites and apps, including Gmail, Google Docs, Microsoft Word, Zendesk, Jira and Salesforce, so you do not need to copy and paste. Grammarly says you can turn it off in any app when you would rather it did not see a piece of writing, and that its apps ignore sensitive fields such as passwords and payment details on a best-efforts basis.

ChatGPT mostly works in its own app on web, desktop and mobile. You bring your text to it and take the result back. OpenAI says ChatGPT Work can connect to your work files and apps, such as Gmail and Slack, to create finished deliverables, so it is moving closer to where you work, but for everyday typing Grammarly is the one that sits inside your apps.

Students and academic integrity

Both tools target students, in different ways. Grammarly leans into proving your work is your own. Its Authorship feature records how a document was written, showing what was typed, pasted or AI-assisted, and Grammarly says you decide when to share the Authorship report, and it does not send it to your professor or anyone else automatically. Grammarly also offers an AI Detector, which it says can identify text from ChatGPT, Gemini, Claude and other tools, a Plagiarism Checker, a Citation Finder and an AI Grader that estimates a grade against your rubric. Grammarly itself notes that AI detectors can get it wrong, so treat any score as a guide, not proof.

ChatGPT's answer is study mode, which OpenAI describes as step-by-step guidance instead of quick answers, with hints, knowledge checks, quizzes and progress tracking. It is better for learning a topic; Grammarly is better for polishing and documenting the essay you write about it. Always follow your school's rules on AI use.

Privacy and your data

Both companies may use what you write to improve their models on personal plans unless you opt out. Grammarly says its Product Improvement and Training setting is on by default for Free, Premium and single-user Pro accounts, and you can switch it off in your account settings. It is off by default for Education accounts and for accounts bought through Grammarly's sales team, while multi-user teams that buy online start with it on until an admin turns it off. Grammarly also says it never sells your content or lets third parties use it to train their models.

OpenAI says data sharing is on by default for personal ChatGPT accounts, and you can turn off "Improve the model for everyone" in Data controls and keep your chat history. Temporary chats are not used to train its models. OpenAI says it does not use content from ChatGPT Business, Enterprise or Edu workspaces for training by default. If you handle sensitive work writing, check these settings in whichever tool you choose.

Teams and business

For teams, Grammarly focuses on consistent writing. Its paid plans add a shared style guide, brand tones, snippets and analytics, and Enterprise adds controls such as confidential mode, data loss prevention, custom roles and bring-your-own-key encryption. It is a strong fit for support, sales and marketing teams that send a lot of customer-facing writing.

ChatGPT Business gives teams a shared workspace with company context, plugins, admin controls and flexible seats, plus ChatGPT Work for multi-step tasks and Codex for engineering. It is the broader platform, while Grammarly is the more specialised writing layer that works across all your other tools.

Pricing models

Both have a free plan. Grammarly's Free plan covers spelling and grammar, tone detection and a small monthly allowance of AI prompts. Pro, for individuals and teams, adds full-sentence rewrites, tone adjustments, plagiarism and AI text detection and a much larger prompt allowance, and Enterprise is sold through sales.

ChatGPT has a Free plan plus several paid individual tiers, which OpenAI lists as Go, Plus and Pro, with more messages, uploads, memory, deep research and advanced models as you move up. OpenAI says the Go plan may include ads. Business and Enterprise plans are priced separately. Plans and prices change, so check the live Grammarly plans page and ChatGPT pricing page before you buy.

Can you use Grammarly and ChatGPT together?

Yes, and many writers do. A common workflow is to brainstorm and draft in ChatGPT, then move the text into your document or email and let Grammarly catch errors, smooth the tone and keep it consistent with your style guide. Just keep your organisation's or school's AI rules in mind, and remember that the final text is still your responsibility.

Who should pick which

Pick Grammarly if:

• You already know what you want to say and mainly need clean, correct, well-toned writing.
• You write across many apps, such as email, docs, chat and CRM tools, and do not want to copy and paste.
• You are a student who wants plagiarism checks, citations and a record that shows your work is your own.
• Your team needs a shared style guide and brand tone applied to everyday writing.

Pick ChatGPT if:

• You often start from a blank page and want drafts, outlines and ideas.
• You want one assistant for writing, research, analysis, images and voice.
• You want to learn a subject step by step, not just polish an essay.
• You need work tasks done end to end, such as documents, slides or code, not only writing help.

Looking at other writing and AI assistants? Browse Claude and Jasper on Unloc, or read Claude vs ChatGPT.

FAQ

Can ChatGPT replace Grammarly?

For some people, yes. ChatGPT can fix grammar and rewrite text when you paste it in. But it does not check your writing inline as you type in other apps, and it tends to rewrite more than it corrects. If you want precise, suggestion-by-suggestion editing everywhere you write, Grammarly is still the better fit.

Is Grammarly better than ChatGPT for grammar checking?

For everyday proofreading, usually yes. Grammarly is built for real-time grammar, spelling, punctuation, clarity and tone suggestions that you accept one by one, so you can see every change. ChatGPT is better when you want a bigger rewrite or a new draft.

Is Grammarly free?

Yes. Grammarly has a free plan with spelling, grammar and tone feedback and a limited number of AI prompts each month. Pro adds full-sentence rewrites, plagiarism and AI detection and more prompts. Check the live Grammarly plans page for current pricing.

Can Grammarly detect writing from ChatGPT?

Grammarly says its AI Detector can identify AI-generated text from ChatGPT, Gemini, Claude and other tools and shows how much of a text appears to be AI-written. Grammarly also notes that AI detectors can get it wrong, so treat the result as a guide. Its Authorship feature is a different approach: it records how you wrote a document.

Do Grammarly and ChatGPT use my writing to train their AI?

On personal plans, both may use your content to improve their models by default, and both let you opt out in your settings. Grammarly turns this off by default for Education accounts and accounts bought through its sales team, and OpenAI says it does not train on ChatGPT Business, Enterprise or Edu workspace content by default.