Grammarly suits people who already write and want every email, doc and post checked where they type it, with 100 AI prompts a month on the free plan. ChatGPT suits people who want help drafting, researching or rethinking from scratch, with unlimited everyday text chats on its free tier. Most business owners end up using one to draft and the other to polish.
These two get lumped together as AI writing tools, but they sit at opposite ends of the job. One watches you write. The other writes when you ask. I read Grammarly's plans page and OpenAI's ChatGPT Free Tier FAQ, so the details below are what each company says about its own product.
Grammarly and ChatGPT free versions compared
| Grammarly | ChatGPT | |
|---|---|---|
| Free version | Yes, Free | Yes, Free tier |
| Main job | Corrects and improves what you write | Drafts, answers and analyses on request |
| Where it works | Docs, desktop, mobile and browser | The ChatGPT app and website |
| AI generation on free | 100 AI prompts a month | Unlimited everyday text chats (abuse safeguards apply) |
| Tone help | See your writing tone (adjust tone on Pro) | Ask it to rewrite in any tone |
| Plagiarism and AI detection | On Pro | Not offered |
| Files and images | Not the focus | Uploads, image creation, data analysis (separate limits) |
| Team features | Style guide and brand tones on Pro | Business and Enterprise workspaces |
Grammarly: the editor that sits beside you
Grammarly's free plan checks spelling and grammar as you type, shows you how your writing comes across, and lets you generate text with 100 AI prompts a month. It works in documents, on desktop, on mobile and in the browser, so it follows you into email, LinkedIn and your CMS.
Pro rewrites full sentences with a click, adjusts tone, helps non-native speakers write fluently in English, and detects plagiarism and AI-generated text, with 2,000 AI prompts per member a month. For teams it adds a style guide and brand tones, which is handy when several people write in your company's name.
ChatGPT: the assistant you talk to
OpenAI's help centre says ChatGPT is free to use, with unlimited everyday text chats, web search, file and image uploads, data analysis, image creation and a Library with 500 MB of storage. Uploads, image generation, voice and data analysis each have their own limits, and ChatGPT tells you when you reach one.
OpenAI also notes that the default model and limits on the free tier can change over time, and that ads may appear in the Free tier in some countries. So the free tier you sign up for today may not look the same in a few months.
If you're new to it, my ChatGPT prompts for better business content will save you a lot of trial and error.
The detail that changes how you use them
Here's what most people miss. Grammarly's free AI generation stops at 100 prompts a month, while ChatGPT's free everyday text chats aren't capped in the same way. So if you want an AI to draft for you, ChatGPT's free tier goes further. But ChatGPT only helps when you copy text into it, while Grammarly checks every sentence where you're already typing. They solve different problems, which is why running both can make sense.
One more ChatGPT change worth knowing: OpenAI says new custom GPTs can no longer be created on personal accounts, including Free and Plus. You can still use existing GPTs, and Business workspaces can still create them.
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Who each one suits
Grammarly suits anyone who writes a lot of short business text and wants fewer typos, clearer sentences and a consistent tone. ChatGPT suits anyone who stares at a blank page, needs ideas or wants to turn notes into a first draft. For a wider view of the options, see my guide to AI writing tools for small business owners.
My advice for everyday business writing
Use ChatGPT to get from nothing to a rough draft, then read it yourself and add the stories and specifics only you know. Then let Grammarly catch the slips as you edit and send. If you can only pick one, ask yourself whether your problem is starting or finishing. Starting points to ChatGPT. Finishing points to Grammarly.
Do you make writing or AI assistant software? Tool makers can ask to be considered for a featured place in comparisons like this one.
Frequently asked questions
Is Grammarly free?
Yes. Grammarly's free plan checks spelling and grammar, shows your writing tone and includes 100 AI prompts a month.
Is ChatGPT free?
Yes. OpenAI's help centre says ChatGPT is free to use, with unlimited everyday text chats and separate limits on uploads, images, voice and data analysis.
Can ChatGPT check my grammar?
It can if you paste your text in and ask. Grammarly checks as you type in documents, email and the browser, without copying anything across.
Does Grammarly detect AI-generated text?
Yes, on the Pro plan, along with plagiarism detection.
