What diff modes are available?

Three modes are supported: Line mode compares full lines, Word mode highlights individual word changes within each line, and Character mode highlights single-character differences — useful for catching subtle typos or punctuation changes.

Does the diff checker work with large texts?

Yes. The LCS algorithm is implemented in pure JavaScript and runs entirely in your browser. Performance is excellent for typical documents. Very large inputs (tens of thousands of lines) may take a moment to process.

What does the similarity percentage mean?

Similarity is calculated as (2 × matched tokens) / (total tokens in both texts), expressed as a percentage. A score of 100% means the texts are identical; 0% means they share no tokens at all.

Can I ignore whitespace differences?

Yes. Enable the "Ignore whitespace" toggle before clicking Compare and the tool will strip leading/trailing whitespace from each line (or collapse internal spaces in word/character mode) before diffing.

Text Diff Checker

Name: Text Diff Checker
Availability: InStock
Author: Nham Vu

Paste two texts, pick a diff mode, and instantly see what changed — additions in green, deletions in red.

Original

Modified

Diff mode:

Case-sensitive Ignore whitespace

Summary

Paste two texts, pick a diff mode, and instantly see what changed — additions in green, deletions in red.

How it works

Paste or type your original text into the left textarea.
Paste or type your modified text into the right textarea.
Select a diff mode: Line, Word, or Character.
Toggle case-sensitive and whitespace options as needed.
Click Compare to view the side-by-side diff with color-coded changes and similarity stats.

Use cases

Reviewing document edits before publishing
Comparing code snippets or configuration files
Proofreading translated or revised manuscripts

Frequently Asked Questions

Last updated: 2026-06-09 · Reviewed by Nham Vu