How does the text diff tool work?

Paste two versions of any text into the left and right panels and the tool highlights every line that was added, removed or changed. Differences are color coded so you can scan results at a glance.

Can I compare long documents?

Yes. The tool handles documents up to roughly ten thousand lines comfortably in any modern browser. Larger texts still work but may take a second or two to render.

Does the diff show character-level changes?

When two lines are mostly the same, the tool highlights the specific characters that differ within those lines, not just the whole line. This makes typo and small edit spotting much faster.

Is whitespace ignored?

By default whitespace is treated as significant, because trailing spaces and tab differences often matter in code. Toggling the option would require local edits 鈥?for prose, trimming both sides first is the cleanest approach.

Is my pasted text uploaded anywhere?

No. The entire comparison runs in your browser. Nothing leaves your device, which makes the tool safe for sensitive legal, financial or proprietary text.

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Text Diff

Compare two texts and instantly see what’s different. Line-by-line highlighting.

Instant Line-by-Line Private

Original Text

Modified Text

How it works

Three simple steps —everything happens in your browser.

Paste both versions

Put your original text on one side and the edited version on the other so the tool can compare them line by line.

Choose your diff view

Switch between unified and side-by-side layouts to inspect additions, deletions, and unchanged lines in the clearest format.

Review changes quickly

Use the stats summary and highlighted output to spot what changed before copying, debugging, or sharing revisions.

Features

Line-by-Line Diff

Compares texts line by line and highlights additions, deletions, and unchanged content.

Two View Modes

Unified view shows all changes in one column. Side-by-side shows both texts with aligned diffs.

Change Statistics

See how many lines were added, removed, and unchanged at a glance.

100% Private

Your text never leaves your browser. No server uploads, no storage.

Why choose ToolKnit Text Diff?

Side-by-side diff

Color-coded additions, deletions, and modifications shown line by line.

No data leaves your browser

Your text stays on your device. Safe for comparing sensitive code and configs.

Instant results

LCS-based diff algorithm runs in your browser with no server round-trip.

Pro Tips

● Great for comparing code, configs, API responses, or any text documents.
● Use Swap to quickly reverse which text is original vs. modified.
● The diff algorithm uses the Longest Common Subsequence (LCS) method for accurate results.