See what the AI changed in your writing

You asked an AI to tidy your email, and it came back smoother. It may also have moved a date or turned “should” into “must”. Paste both versions and Edit Check lists every detail that changed or went missing, and anything the AI added. Nothing you paste leaves this browser.

Checking a summary rather than an edit? Summary Check traces each line to the original.

New to this? What it does, in plain words

It compares what you wrote with what the AI gave back, and points at the details that are no longer the same.

Use it whenever an AI edits your own words: an email made shorter, a report made clearer, an essay polished, a cover letter tightened. A manager can check that a deadline survived the rewrite. A student can see that the essay still makes the claim they made. Someone writing in a second language can see exactly what the AI altered.

What you need

Your original text and the AI’s version. No API key and no sign-up. Both texts are read in this browser and sent nowhere.

How to use it

Paste what you wrote on the left and the AI’s version on the right. The check runs as you paste.
Read the list. Changed and added details come first, because those are the ones that cause trouble.
Press Keep the change on anything you are happy with.
Copy the prompt at the bottom, or open it in your AI, to have the rest put back exactly as you wrote it.

What you wrote

Your original text

What the AI gave back

The AI's version

Both texts stay on this device. The check is done by rules in this page, with no AI and no upload.

Paste both versions to see what changed. Numbers, amounts, dates, days, times, names, quotes and links are compared one by one.

Where to next

Why a polished rewrite still needs a second look

An AI edits for flow. It does not know which of your details are fixed and which are free to change, so a clean rewrite can quietly carry a different date.

From two versions to a short list

In your browser. Paste both versionsYour own text, and what the AI gave back.
In your browser. Details are matchedEvery number, date, name, quote and link in one is looked for in the other.Instant
In your browser. Read the short listWhat changed, what is gone, what is new, and where the tone got firmer.
In the AI you use. Have it put rightOne prompt that asks for those corrections and nothing else.

What it looks for

Details that changed. A date, an amount, a percentage, a time or a name that is in your text and reads differently in the rewrite.
Details that went missing. The person you named or the deadline you gave, gone from the new version.
Details that were added. A year or a name you never wrote. An AI filling a gap is the usual cause.
Numbers that sound more exact. “About 12%” that became “12%”, or “up to 40” that became “40”.
Sentences that got firmer or softer. “Should” turned into “must”, or a “not” that came or went.
Whole sentences. Ones you did not write, and ones of yours with no match in the new version.

You asked an AI to make this shorter: “We may need a second truck, which would add roughly $900.” Which rewrite changed what you said?

“A second truck may be needed, adding roughly $900.”
Not quite. Shorter, and every detail is the same: still “may”, still “roughly $900”.
“We will need a second truck, which adds $900.”
Yes. “May” became “will” and “roughly” is gone. The reader now expects a certain cost of exactly $900. Edit Check lists both changes.
“A second truck might be needed, at a cost of about $900.”
Not quite. “Might” and “about” say the same as “may” and “roughly”. Nothing a reader relies on has moved.
“We might need a second truck (roughly $900 more).”
Not quite. The wording changed and the claim did not.

The words an AI trims first are often the careful ones: about, roughly, may, should.

What it cannot do

It compares details, not meaning. A rewrite can keep every number and still shift the sense of a sentence, and rules cannot see that. It can also flag a change that is harmless, such as “cannot ship before the test” becoming “can ship once the test is done”. Treat the list as where to look first, then read the new version once yourself. Names are found by their capital letters, so a name written in lowercase is missed.

Questions

How do I see what ChatGPT changed in my text?

Paste your original on the left and ChatGPT’s version on the right. The list shows every detail that changed or went missing and anything that was added, and the section below it marks every word that was taken out or put in. The same works for Claude, Gemini, Copilot and any other AI.

Does my text go anywhere?

No. Both texts are compared in this browser and nothing you paste is sent to thinkhard.si or anyone else. They are kept in this browser so they survive a reload, and Clear both removes them. Only if you press Open in ChatGPT or Open in Claude does the correction prompt go to that app, because you sent it there.

Is this the same as a text compare or diff tool?

It includes one: the word-by-word section shows every insertion and deletion. The list above it is the part a plain diff does not give you. It reads “March 14” and “14 March” as the same date and “five” and “5” as the same number, so only real changes are listed. Then it tells you which of them touch a fact a reader will rely on.

Why does it flag a change that looks fine to me?

Because it cannot know which details matter to you. If the AI corrected a date you had wrong, press Keep the change and the item leaves the correction prompt.

How do I stop an AI changing my facts when it edits?

Say so in the request: “Edit for clarity and length. Keep every number, date, name and quote exactly as written, keep words such as about, roughly, may and should, and do not add facts.” The Prompt Builder adds lines like these for you, and the plain language rewrite prompt has them built in.

Does it work in other languages?

The word-by-word comparison works in any language. Numbers, amounts, links and dates written in digits are matched in any language too. Month and weekday names are read in English only, and so are the words for certainty, such as “about” and “must”.