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Text Diff Checker

Paste the original and the revision. See exactly which lines were added, removed or left alone before you accept an AI rewrite or submit the second draft.

Runs in your browserUpdated November 9, 2026Line-by-line diff · Similarity score · Nothing uploaded

The short answer

A text diff checker compares two pieces of text line by line and highlights additions, deletions and unchanged content. This browser tool shows line numbers, an added/removed count, a similarity percentage and a copyable diff, so you can review a rewrite without uploading either version.

Original version5 lines

Revised version5 lines

Hide unchanged lines

Added lines

Removed lines

−4

Similarity

20%

Shared lines

Line-by-line diff

11The report analyses monthly sales for the northern region.

2−The dataset contains 1,240 rows and 8 columns.

3−Revenue increased by 12% between January and June.

4−The dashboard uses a pivot table and one slicer.

5−The conclusion recommends expanding the current campaign.

2+The dataset contains 1,240 rows and 9 columns after cleaning.

3+Revenue increased by 14% between January and June.

4+The dashboard uses two pivot tables and one slicer.

5+The conclusion recommends expanding the current campaign in Q3.

The comparison is line by line. A rewritten sentence counts as one removed line and one added line, even when the meaning is unchanged.

How to use it

1Paste the original version into the left panel and the revision into the right.
2Review the added, removed and similarity counts.
3Tick “Hide unchanged lines” to focus on the edits.
4Copy the diff into your notes or keep it with the assignment version history.

Questions about the text diff checker

Is either version uploaded?

No. The comparison runs entirely in your browser. The two texts are not sent to a server, saved in an account or included in analytics.

How is similarity calculated?

It is the number of unchanged lines divided by the longer document's line count. It is a quick signal, not a plagiarism or AI-detection score. Reflowed paragraphs can lower the percentage even when the meaning is unchanged.

Why does a small edit show as a big diff?

The comparison is line based. Changing one word creates a removed line and an added line. Use the line numbers to see what moved and what was genuinely deleted.

Is there a size limit?

The comparison is capped at 1,500 lines per side to keep the browser responsive. Longer documents show a truncation notice; split them into sections if you need a complete review.

Can I compare an AI rewrite with my original?

Yes. That is the main use case. Check whether the rewrite changed a fact, dropped a citation or altered the conclusion before you keep it.

Need it done for you?

Comparing two workbooks rather than two drafts?

The Compare Lists tool finds matches and differences between two columns. For a full workbook audit, send both files and a human expert will reconcile the formulas and values.

Get a fixed quote Ask on WhatsApp See pricing →

From $15/hr
Fixed quote before work starts
Free minor revisions
Human experts, not AI files

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