What is Text Diff Checker?

Text Diff Checker is a free online tool for comparing two texts and visually identifying their differences. Whether you're reviewing code changes, checking document revisions, or verifying configuration file edits, this tool makes it easy to spot what's changed.

The tool offers two comparison modes to suit different needs. Choose between real-time comparison as you type, or enter your texts first and compare them all at once with a button click. Since everything runs in your browser, you can safely compare texts containing personal or confidential information without privacy concerns.

What You Can Do

• Two Comparison Modes: Choose between real-time comparison or button-triggered comparison
• Side-by-Side Comparison: View original and modified text next to each other for easy comparison
• Detailed Change Statistics: Automatically tracks the number of added/deleted lines and change locations
• Large File Support: Smoothly handles long documents and code files with thousands of lines
• Completely Private: All data is processed in your browser and never sent anywhere

How to Use

Choose a Comparison Mode

Select the mode that best fits your needs:

Default Mode (Recommended)
Enter both texts before and after changes, then click the "Compare" button to view differences. Perfect for longer texts or when you want to review multiple edits at once.

Real-time Mode
Changes are color-coded and displayed instantly as you type. Ideal for shorter texts or when you want to see differences while making gradual edits.

Basic Steps

For Default Mode

1. Enter Your Texts: Type or paste the text before changes on the left and after changes on the right
2. Click Compare: Press the "Compare" button
3. Review Results: Differences are color-coded, with statistics pinned at the top for easy reference

For Real-time Mode

1. Enter Your Texts: Type or paste text in both areas
2. See Instant Results: Changes are automatically color-coded as you type

Customize the Display

Both modes allow you to adjust the view to your preference:

Line Numbers
Display line numbers on the left side. Helpful for identifying which lines changed in longer texts.

Gutter
Show vertical markers between panels where changes occur. Makes it easy to spot modified sections at a glance.

Highlight Changes
Highlight specific characters that changed. When off, only entire lines are highlighted.

Line Wrap
Automatically wrap long lines to fit your screen width. No horizontal scrolling needed.

Understanding the Statistics

The statistics displayed above the comparison results stay pinned as you scroll, so you can always reference them even with long texts:

Lines Added / Lines Deleted
The number of lines added to and removed from the modified text. This gives you a quick sense of how much changed.

Change Blocks
The number of separate change locations. Consecutive changed lines count as one block. For example, if you modify 3 lines in a row, that's "1 block." If you change 2 separate locations, that's "2 blocks."

Original / Modified
The total line count for each text. Useful for understanding the overall size of your documents.

When to Use This Tool

Code Review
When reviewing code changes, see exactly what was modified. Default mode is perfect for reviewing complete changesets at once.

Document Revision Checks
Compare versions of contracts, specifications, or manuals to identify precisely what changed between versions.

Configuration File Changes
Verify that only intended changes were made when editing system or application configuration files.

Writing and Editing
Compare drafts to see how your text evolved during the editing process. Real-time mode lets you refine your text while watching the changes.

Privacy and Security

All text you enter is processed entirely within your browser. Nothing is ever sent to any server, so you can safely use this tool with confidential or personal information.