AI Grammar Checker: How to Proofread and Improve Your Writing With AI

An important email to a client, a cover letter, an internship report, a listing to sell your car, a message in the school parents’ group chat: sometimes one typo or clumsy sentence is enough to spoil the impression you want to make. Good news: checking spelling and grammar and improving your writing with AI has become simple, fast, and free.

You still need to know what you’re asking for, though. “Fix this text” can mean two very different things: fix the mistakes and leave everything else alone, or rewrite your sentences to make them clearer. And that’s exactly where the trouble starts if you don’t spell it out. In this guide, I’ll show you how to use an AI grammar checker like ChatGPT or DeepL Write, with a step-by-step method, copy-and-paste prompts, and the pitfalls to avoid so the AI doesn’t change what you meant to say.

Contents

1. Proofreading vs. improving: two different requests
2. Which tool should you use to proofread?
3. Step-by-step: how to proofread a text with AI
4. Copy-and-paste proofreading prompts
5. Real-world examples for different kinds of writing
6. Going further: rephrasing and other languages
7. Mistakes and limitations to know about
8. My checklist before sending an AI-proofread text
9. FAQ
10. The bottom line

Proofreading vs. improving: two different requests

Before you paste your text, ask yourself: what exactly do you want from the AI? In my own use, I distinguish four levels of editing, from lightest to deepest.

Level	What the AI does	When to use it
Proofreading	Spelling, grammar, agreement, punctuation	Text that’s already well written, you just want zero mistakes
Light edit	Proofreading + repetition and clunky phrasing	Work email, letter, social post
Improvement	Clarity, flow, tone, sentence length	Rough draft, written fast, too long
Rewrite	New structure, new wording	Text you need to transform for another audience or purpose

The further down this table you go, the more liberties the AI takes, and the greater the risk it makes you say something you didn’t mean. That’s why I recommend always stating the level you want in your request. “Only fix the mistakes” gives you a very different result from “improve this text.”

There’s also the question of style. If you have your own way of writing, a vocabulary, a sense of humor, a way of turning a phrase, a full rewrite risks erasing it. I find that pure proofreading is often the best option for personal writing, while improvement is more useful for practical texts, where clarity matters more than personality.

Which tool should you use to proofread?

Several AI tools can proofread and improve a text. Here are the two I cover in this guide, because between them they handle most needs.

ChatGPT: the most versatile

ChatGPT can fix spelling and grammar, but it can also rephrase, change the tone, simplify, or restructure a text. You can paste your text straight into the chat or upload a file. The free version is plenty for proofreading emails, letters, or everyday documents. The Plus subscription costs $20 a month and gives you higher limits, but you don’t need it to proofread something now and then. If you’re on the fence, read my article on free ChatGPT.

Its big strength is the conversation: you can ask for a proofread, then a shorter version, then a warmer version, then go back, all in the same chat. Its weakness: if you don’t frame the request, it tends to rewrite too much.

As for age, ChatGPT requires you to be at least 13 (or the minimum age in your country), with a parent’s permission if you’re under 18.

ChatGPT for Word: proofread right inside Word

Since September 17, 2026, OpenAI has offered ChatGPT for Word. It lets you revise a selected passage, draft from notes, summarize, or change headings and formatting, right inside your Word document. It’s available on all plans, including the free version, with limits that depend on your plan. Handy if you already work in Word and don’t want to copy and paste between two windows.

DeepL Write: the specialized proofreader

DeepL Write is a tool built for writing: it fixes spelling, grammar, and punctuation, rephrases, and improves clarity and style. The free version accepts up to 1,500 characters at a time, about one long paragraph or a short email. DeepL Pro Translator users can go up to 2,000 characters, and the Write Pro plan removes those limits for $7.49 per user per month, billed annually, as an add-on to the eligible plans.

In my experience, DeepL Write is really comfortable for short texts: you see the suggested changes and pick what you want. For a long document or a major rewrite, I prefer ChatGPT, which accepts much longer texts and lets me explain the context.

Step-by-step: how to proofread a text with AI

Here’s the method I use for all my important writing. It takes two or three minutes and saves you from nasty surprises.

1. Read your text once yourself, quickly, to make sure the content is right: the AI won’t fix wrong information.
2. Remove sensitive information (names, addresses, case or account numbers) if it isn’t needed for the proofread.
3. Specify the level of editing: proofreading only, light edit, improvement, or rewrite.
4. Give context: who the text is for, what it’s for, and what tone you want.
5. Ask for a list of changes, so you know what was modified.
6. Reread the corrected version side by side with the original, especially the key sentences.
7. Adjust if needed: “keep my wording for the second sentence,” “that’s too formal,” and so on.

Copy-and-paste proofreading prompts

Here are my most useful prompts, from the most cautious to the most ambitious. Just replace the parts in brackets.

Pure proofreading, style untouched

This is the prompt I use most. It fixes mistakes and nothing else.

Fix only the spelling, grammar, verb tense, and punctuation mistakes in this text. Don’t change the style, the vocabulary, or the sentence structure. Don’t rephrase anything. Give me the corrected text, then a list of the corrections you made in the format “before → after.”

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[text]
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Proofreading with explanations, so you improve

If you want to understand your mistakes and stop making them, ask for simple explanations.

Fix the mistakes in this text. For each one, explain the rule in one simple sentence, as if to someone who has forgotten their grammar lessons. Finish with the 3 mistakes I make most often and a tip for each.

Light edit

Review this text the way a professional copy editor would: fix the mistakes, flag repetition and sentences that are too long or ambiguous, and only suggest an alternative when it’s truly necessary. Keep my tone and vocabulary.

Improve clarity

Make this text clearer without changing its meaning or adding information. Shorten sentences that are too long, cut repetition, and replace jargon with plain words. The reader is [a client / a coworker / the general public]. Keep the length close to the original.

Change the tone

Rewrite this message with a more [friendly / professional / diplomatic / direct] tone, without changing the information in it. Give me two versions, one short and one a bit longer.

Simplify a text

Simplify this text so it can be understood by [a teenager / someone who doesn’t know the subject / a reader in a hurry]. Short sentences, everyday words, one idea per sentence. Don’t remove any important information, and tell me if you had to cut something.

Restructure a messy text

This text is disorganized. Suggest a new logical outline, then reorganize the text to follow it, keeping as many of my original sentences as possible. Tell me which passages you moved.

Shorten

Shorten this text to about [number] words while keeping the essentials: [information that must stay]. Cut repetition and filler phrases first before touching the substance.

Real-world examples for different kinds of writing

The same method works in very different situations. Here are a few cases I run into often.

A work email

Take Chloe, who needs to reply to an unhappy customer. She wrote a first draft while she was annoyed. She asks ChatGPT to fix the mistakes, then to make the tone more diplomatic while keeping her position. She then rereads the suggested version and puts back one sentence of her own that she felt was more accurate. To go further on this, see my guide to writing emails with ChatGPT.

Fix the mistakes in this email and make the tone more diplomatic, without apologizing for things I’m not responsible for and without changing my position on [specific point].

A cover letter or resume

Here, zero mistakes is a must, but the letter has to stay yours. I recommend a pure proofread, then a light edit, while rejecting the overly generic phrasing the AI might suggest.

Fix the mistakes in this cover letter. Then point out any sentences that seem bland or too vague, without rewriting them: I want to rework them myself.

A homework assignment or thesis

For school or college work, spelling and grammar correction is usually accepted, but rewriting the content can be a problem. Check your school’s policy. The “proofreading with explanations” prompt is ideal here, because it helps you improve.

A social media post or listing

Proofread this text and suggest a catchier version of the first sentence. Keep a natural tone, not salesy, and a similar length.

Creative writing

For a poem, a story, or song lyrics, be very careful with rewriting: AI tends to smooth out original phrasing. Ask only for proofreading, or for suggestions you pick yourself. If you write lyrics, you’ll like my guide to making a song with AI, as well as my article on Suno AI.

Going further: rephrasing and other languages

Proofreading is often just the first step. Once your text is clean, you may want to rephrase it completely for another use: I cover that in detail in my guide to rewriting a text with AI. And if you write in another language, AI can proofread a text in Spanish, French, or German with the same method; just specify the language and the level of formality you want.

Proofread this text in Spanish. I’m a native English speaker: also point out any phrases that sound “translated from English” and suggest more natural wording.

Mistakes and limitations to know about

An AI grammar checker is very effective, but it’s not foolproof. Here are the pitfalls I’ve learned to watch for.

AI can change the meaning

This is the main risk. When rephrasing, AI can shift a nuance (“it’s possible that” becomes “it’s certain that”), drop a negation, flip a timeline, or soften a statement you wanted to be firm. In a contract, an official letter, or a sensitive message, these small slips can have consequences.

Compare my original version with your corrected version. List every sentence whose meaning may have changed, even slightly, and explain the difference.

AI can add information

When you ask it to “improve” a text, AI sometimes adds sentences, examples, or details that weren’t in the original. Reread to make sure nothing was made up.

Proper nouns and technical vocabulary

Last names, brand names, industry terms, acronyms: AI can wrongly “correct” them. Flag them in your prompt if needed.

A style that’s too uniform

If you have AI correct everything, your writing can start to sound the same and lose your voice. I find this especially noticeable in personal writing. Stay in charge of what makes your style yours.

Privacy

Proofreading a text means sending it to an online service. Before pasting a document:

• Remove personal data that isn’t needed for the proofread: names, addresses, numbers, health information.
• Follow your employer’s rules: some internal documents shouldn’t be sent to an outside tool.
• Check the data settings of the tool you use, especially whether your conversations are used to improve the models.

My checklist before sending an AI-proofread text

• I specified the level of editing (proofreading, light edit, improvement, rewrite).
• I asked for and read the list of changes.
• I checked that the meaning of key sentences didn’t change.
• No information was added or removed without my OK.
• Proper nouns, numbers, and dates are correct.
• The text still sounds like what I usually write.

FAQ

What’s the best free AI grammar checker?

There’s no single answer. Free ChatGPT is the most versatile, because it proofreads, rephrases, and explains its corrections on long texts. Free DeepL Write is very handy for short texts, up to 1,500 characters at a time. Personally, I switch between them depending on the length of the text.

Can AI replace a human proofreader?

For everyday writing, it’s a huge help. For a book, a legal document, or an important publication, I find a human review is still valuable, because AI can miss errors in meaning or introduce unwanted changes.

How do I keep AI from rewriting my whole text?

Be explicit: “only fix the mistakes, don’t change the style or vocabulary, don’t rephrase anything.” Also ask for the list of corrections: you’ll see right away if the AI went too far.

Can you proofread a Word document with ChatGPT?

Yes, in two ways: by uploading the file to ChatGPT, or with ChatGPT for Word, available since September 17, 2026 on all plans (with limits depending on the plan), which lets you revise a selected passage right in Word.

Is it OK to proofread homework with AI?

It depends on your school and your teacher. Spelling and grammar correction is often tolerated; rewriting the content much less so. When in doubt, ask, and stick to prompts that explain the rules, so you learn instead of outsourcing.

Can AI proofread texts in other languages?

Yes. ChatGPT and DeepL Write handle several languages. Specify the language and level of formality, and ask it to spot phrasing that sticks too closely to English.

The bottom line

To check spelling and grammar and improve your writing with AI, the golden rule is to say exactly what you want: pure proofreading, a light edit, an improvement, or a rewrite. Always ask for the list of changes, make sure the meaning hasn’t shifted, and stay in charge of your style. ChatGPT is the most versatile, DeepL Write is ideal for short texts, and ChatGPT for Word lets you work directly in your documents.

To go further, check out my guide to writing a good prompt and my tips for rewriting a text with AI.