You edit the document. AI gives a second opinion when you ask.

StetProof lets you correct an HTML document right on the page. AI can explain a passage, review the whole document or suggest a better sentence, and its suggestions wait in the margin until you decide what to do with them.

Open the web app The Chrome extension isn’t in the Chrome Web Store yet.

Free while it’s in beta. No account, and your files stay on your computer.

Why it exists

A lot of documents now arrive partly written by AI. The usual way to improve one is to ask the AI again, and you get a new version with different problems and no easy way to see what moved.

StetProof works the other way round. You do the editing. AI reads along and offers advice, and it cannot change a word unless you give it permission and then accept each change yourself.

The name comes from proofreading. Stet is Latin for let it stand: an editor writes it in the margin when a correction should be ignored and the original kept.

What it does

Edit by hand: Click any text on the page and type. You can add paragraphs, list items and table rows, and make words bold or italic. The file you save is the file you opened, with your changes and nothing else.
Ask for advice: Select a passage and ask AI to explain it, or have it review or proofread the whole document. Its answers appear beside the text, never in it.
Accept changes one at a time: If you let AI suggest edits, each one gets an Accept button. Nothing is applied until you press it.
Know who changed what: Every edit is listed with its author, whether that is you, a colleague or an AI model, and any of them can be undone on its own.
Keep the review with the file: Comments and replies sit in the margin and are saved inside the HTML, so whoever gets the file next can read them.
Notice outside edits: If someone else’s tool rewrites the file while you work, StetProof highlights what changed and keeps your unsaved edits.

AI, if you want it

AI is off until you add your own API key for Anthropic, OpenAI, OpenRouter, Google Gemini or a model running on your own computer. You pay the provider directly. With a key added you can ask it to explain a passage, proofread the document, suggest a rewrite or draft a reply to a comment.

Out of the box it can only make suggestions, which you read and then act on yourself. If you switch it to Read and write, its suggestions get an Accept button and nothing changes until you press it. Every change the AI takes part in is listed under the name of the model.

Questions

Can AI edit my document without asking?

No. By default AI can explain, review, reply to comments and suggest wording that you copy if you like it. If you switch it to Read and write, its suggestions get an Accept button. Either way, nothing changes until you act.

Is my document uploaded anywhere?

No. StetProof opens and edits the document in your browser, and there is no StetProof server to send it to. If you turn on AI, the paragraphs you ask about go to the AI service you picked, and only when you press the button.

Which browsers does it work in?

The web app runs in any current browser. In Chrome or Edge on a computer, Save writes back to the file you opened. Other browsers download the edited copy for you to save yourself.

What can’t it change?

Layout, styles and images are left alone. StetProof changes words, and can add paragraphs, lists, tables, bold and italic in the same style as the ones already in the document. Pages that build their text with JavaScript can’t be edited, because the words aren’t in the file.

Do I need AI to use it?

No. All the editing works without it, and AI stays off until you add a key.

Is it free?

Yes, while it’s in beta, with no account and no card. If that ever changes, it will be announced on this page first. AI usage is billed by your AI provider at their prices; StetProof adds nothing.

Open the web app