How it Works

Diff Checker is an online tool designed to compare two text files or strings and highlight their differences. It utilizes the Myers Diff Algorithm to identify changes line-by-line or character-by-character.

Whether you are debugging code, reviewing document revisions, or verifying data lists, this tool helps you visualize additions (green) and deletions (red) instantly.

Use Scenarios

Developers & Programmers

Quickly compare code snippets before committing. Identify changes in configuration files or debug output logs.

Writers & Editors

Compare drafts and revisions to see exactly what has changed in an article or manuscript.

Legal & Business

Review contract drafts to ensure no unauthorized changes were made to the terms and conditions.

Data Verification

Compare two lists (e.g., email lists or user IDs) to find missing or added entries efficiently.

FAQ

Is my data secure?

Yes, absolutely. This tool is a client-side application. All comparisons happen locally in your browser, and your text is never sent to any server.

Why are line breaks marked as differences?

Computers treat whitespace and line breaks (like Windows CRLF vs Mac LF) as characters. In "Char Comparison" mode, these invisible differences are flagged.

Is there a file size limit?

Since it runs in your browser, performance depends on your device. Comparing files with tens of thousands of lines works fine, but extremely large files may slow down the browser.

Can I compare Word or PDF files?

Currently, this tool supports plain text only. We recommend copying contents from Word or PDF and pasting them into the text areas to compare.

Difference between Char and Line comparison?

"Char Comparison" checks every single letter, ideal for spell checking. "Line Comparison" treats each line as a unit, perfect for code logic or structural changes.

Is this tool free?

Yes, 100% free. No usage limits, no hidden fees, and no sign-up required.

Can I compare code?

Absolutely. It works great with HTML, CSS, JS, Python, Java, and any other text-based programming language.

How to swap text quickly?

Use the "Swap Text" button below the input areas to instantly reverse the Original and Modified texts.

More Free Tools

Text Cleaner

Remove empty lines, duplicate lines, and trim text. Extract emails and URLs easily.

Case Converter

Free online case converter tool. Convert text between Uppercase, Lowercase, Title Case, CamelCase, Snake Case, etc.

Word Counter

Count words, characters, sentences, and paragraphs. Estimate reading time.

JSON Formatter

Beautify, validate, and minify JSON data. Highlight errors and fix formatting.

SQL Formatter

Beautify and format your SQL queries with uppercase keywords and proper indentation.

HTML to Markdown

Convert HTML to Markdown and vice versa. Live preview and clean output.

Text Diff Checker

Comparison Result