Text Diff - Compare Texts Online

About Text Diff - Compare Texts Online

A free online text comparison tool that shows line-by-line differences between two texts. See additions, deletions, and modifications highlighted in real time. Perfect for comparing code, config files, or any text content.

Key Features

Line-by-Line Comparison — See exactly which lines were added, removed, or changed

Visual Highlighting — Color-coded output makes differences instantly visible

Change Statistics — Summary of additions, deletions, and unchanged lines

Swap Function — Quickly swap original and modified text

Fast Algorithm — Uses LCS (Longest Common Subsequence) for accurate diff computation

100% Client-Side — Your text is never sent to any server

How to Use

Paste your original text in the left panel.
Paste your modified text in the right panel.
Click Compare Texts to see the differences.
Green lines are additions, red lines are deletions, and the stats show the total changes.

Use Cases

Code Review: Compare code snippets to see exactly what changed between versions before committing.

Config File Comparison: Diff two configuration files to spot differences that might cause issues.

Document Editing: Compare drafts to see what was added or removed during the editing process.

Contract Review: Compare versions of legal documents or agreements to identify changes.

Tips

Tip: For large files, paste only the relevant sections to get the most useful comparison.

Tip: Use the Swap button to quickly switch between comparing A→B and B→A.

Alternatives

diffchecker.com — Popular online diff tool with file upload

Meld — Desktop diff/merge tool for developers

VS Code Diff — Built-in diff viewer in VS Code

FAQ

This tool uses the LCS (Longest Common Subsequence) algorithm, which finds the longest sequence of lines that appear in both texts. Lines not in the LCS are identified as additions or deletions, giving you an accurate line-by-line comparison.

Yes. All processing happens in your browser using JavaScript. Your text is never uploaded to any server or stored anywhere. You can verify this by checking your browser's network activity — no data is sent.

Absolutely. This tool works with any text content — code, configuration files, documents, or plain text. The monospace font and line-by-line display make it especially useful for code comparison.

Green-highlighted lines are additions (present in the modified text but not the original). Red-highlighted lines are deletions (present in the original but not the modified). Unhighlighted lines are unchanged.

There's no hard limit, but very large files (10,000+ lines) may slow down the comparison since it runs entirely in your browser. For best results, compare sections of 1,000 lines or fewer.

Text Diff Free