How does the Diff Checker mark changes?

Lines that were removed from the first text start with a minus sign, lines that were added in the second text start with a plus sign, and lines that match in both are shown unchanged. You can copy the whole marked-up result with one click.

Does it compare line by line or word by word?

It compares line by line. Two lines are treated as different if they do not match exactly, including spacing. To catch small wording edits, put each sentence on its own line before comparing.

Is my text uploaded anywhere when I compare it?

No. The comparison runs entirely in your browser on your own device, so your text is never sent to a server. That makes it safe for code, private notes, or confidential documents.

Can I compare two pieces of code with it?

Yes. The tool uses a monospaced view, so code, JSON, and config files line up cleanly and the added or removed lines are easy to spot.

Diff Checker | JotTools

Input

Compare against

Output

What the Diff Checker does

This tool compares two blocks of text and shows you exactly what changed between them, line by line. Paste an old version on one side and a new version on the other, and it lays out which lines were added, which were removed, and which stayed the same. It is handy for writers checking two drafts, developers comparing code snippets, students spotting edits in an assignment, and anyone reviewing a contract or config file before and after a change.

The comparison happens entirely in your browser. Your text is never sent anywhere, which makes this safe for code, private notes, or anything you would rather not upload.

How to use the Diff Checker

Paste or type your first (original) text into the main box.
Paste the second version into the “Compare against” field below it.
Click Compare.
Read the result: lines starting with - were removed, lines starting with + were added, and unchanged lines stay as they are.
Hit Copy to grab the marked-up output.

Why use this diff tool

It is free, needs no sign-up, and returns results the instant you click Compare. Because the matching runs locally on your device, even large or sensitive text stays private. The output uses the familiar + and - markers, so the changes are easy to scan at a glance without any colour-coding to decode.

Tip: the check works per line, so to catch small wording changes, keep each sentence or statement on its own line. For more accurate results, trim trailing spaces before you compare, since an invisible space counts as a difference.

This is a quick text comparison, not a full version-control system, so use it for spotting changes rather than tracking project history over time.

Frequently asked questions

How does the Diff Checker mark changes?: Lines that were removed from the first text start with a minus sign, lines that were added in the second text start with a plus sign, and lines that match in both are shown unchanged. You can copy the whole marked-up result with one click.
Does it compare line by line or word by word?: It compares line by line. Two lines are treated as different if they do not match exactly, including spacing. To catch small wording edits, put each sentence on its own line before comparing.
Is my text uploaded anywhere when I compare it?: No. The comparison runs entirely in your browser on your own device, so your text is never sent to a server. That makes it safe for code, private notes, or confidential documents.
Can I compare two pieces of code with it?: Yes. The tool uses a monospaced view, so code, JSON, and config files line up cleanly and the added or removed lines are easy to spot.

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Last updated: June 15, 2026