What is a text difference checker?

A text difference checker (or diff tool) compares two pieces of text and highlights exactly what has been added, removed, or changed. It's widely used by developers, writers, and editors to review changes in code, documents, or any text content.

Is my text kept private?

Yes. This tool runs entirely in your browser. No text is sent to any server, making it completely safe to use with sensitive documents, code, or personal content.

What is a line-by-line diff vs character diff?

A line diff compares texts line by line, marking entire lines as added or removed. A character diff goes deeper, highlighting the specific characters within changed lines that differ, which is useful for catching small typos.

⚡ Free Tool

Text Difference Checker

Paste two texts to instantly see every addition, deletion, and change — highlighted line by line. 100% private, runs in your browser.

Original Text (A)

Modified Text (B)

Diff Result

Enter text in both panels and click "Compare Texts" to see differences.

Features

🔍

Line-by-Line Diff

Each line is compared individually. Added lines are shown in green, removed in red, unchanged in gray.

📊

Diff Statistics

See at a glance how many lines were added, removed, and left unchanged between the two versions.

⇄

Swap Panels

Instantly swap the original and modified texts to reverse the comparison direction.

🔒

100% Private

Your text never leaves your browser. Safe for confidential documents, code, and sensitive content.

How to Use the Difference Checker

Paste Original Text

Copy and paste your original (before) text into the left panel labeled "Original Text (A)".

Paste Modified Text

Copy and paste the updated (after) version into the right panel labeled "Modified Text (B)".

Click Compare

Press "Compare Texts" to instantly highlight all additions (green), deletions (red), and unchanged lines (gray).

Review & Copy

Review the diff results and use "Copy Diff" to share the comparison with your team.

Frequently Asked Questions

A text difference checker (or diff tool) compares two pieces of text and highlights exactly what has been added, removed, or changed. It's used by developers, writers, and editors to review changes in code, documents, and more.

Yes. This tool runs entirely in your browser using JavaScript. No text is ever sent to a server, making it completely safe for confidential documents, proprietary code, or personal data.

Absolutely. The tool works for any plain text: source code, JSON, YAML, Markdown, CSV, or prose. Simply paste the content from both file versions and compare.

This tool uses the Longest Common Subsequence (LCS) algorithm to find the minimal set of changes between two texts. This is the same algorithm used by Git and other version control systems.