Text Diff Checker

What is Text Diff Checker?

Text Diff Checker is a free online tool for comparing two texts and highlighting their differences. It shows line-by-line changes with color-coded highlighting: green for added lines, red for removed lines, and gray for unchanged lines. Perfect for comparing file versions, reviewing changes, or finding differences between documents.

Whether you are reviewing code changes, comparing document versions, or checking text modifications, this tool makes it easy to spot differences at a glance.

How to use Text Diff Checker?

Compare Two Texts

To compare texts:

1. Paste original text in the left field
2. Paste modified text in the right field
3. View differences automatically displayed below
4. Check statistics to see total, added, removed, and unchanged lines

Understanding the Display

Color coding:

• Green background with + prefix: Lines added in modified text
• Red background with - prefix: Lines removed from original text
• Gray background: Lines that are unchanged

Statistics:

• Total Lines: Number of lines in the diff
• Added: Count of new lines
• Removed: Count of deleted lines
• Unchanged: Count of lines that stayed the same

Features

• Side-by-side comparison - View original and modified text together
• Color-coded differences - Green for additions, red for deletions
• Line numbers - Track which lines changed
• Statistics - Summary of changes
• Real-time comparison - Updates as you type
• Monospace font - Clear display for code and formatted text
• Dark theme support - Works in light and dark modes
• No file size limit - Compare texts of any length

Use Cases

1. Code Review

Compare code before and after changes:

Original:

function hello() {
  console.log("Hello");
}

Modified:

function hello(name) {
  console.log("Hello " + name);
}

Result: Shows parameter addition and log message change

2. Document Comparison

Compare different versions of documents:

Original:

Project deadline: December 15
Budget: $10,000
Team size: 5 people

Modified:

Project deadline: December 20
Budget: $12,000
Team size: 6 people

Result: Highlights all three changes

3. Configuration Files

Compare configuration changes:

Original:

port: 3000
debug: false
timeout: 30

Modified:

port: 8080
debug: true
timeout: 60

Result: Shows all modified settings

4. Text Editing

Track changes in text documents:

Original:

The quick brown fox jumps over the lazy dog.

Modified:

The quick brown fox jumps over the sleeping dog.
A new sentence was added.

Result: Shows word change and new line

5. JSON Comparison

Compare JSON configurations:

Original:

{
  "name": "App",
  "version": "1.0.0"
}

Modified:

{
  "name": "App",
  "version": "1.1.0",
  "author": "John"
}

Result: Highlights version change and new field

Tips for Best Results

1. Use consistent formatting: Format both texts similarly for accurate comparison

2. Check line endings: Different line endings may cause extra differences

3. Remove trailing spaces: Trailing whitespace can show as differences

4. One change at a time: For complex diffs, compare incrementally

5. Use for any text: Works with code, documents, configs, logs, etc.

6. Review statistics first: Get an overview before diving into details

Common Diff Scenarios

Added Lines Only

When content is added without removing anything:

• All new lines appear in green
• Original lines remain gray (unchanged)
• Added count increases

Removed Lines Only

When content is deleted:

• Deleted lines appear in red
• Remaining lines stay gray
• Removed count increases

Modified Lines

When lines are changed:

• Old version appears in red (removed)
• New version appears in green (added)
• Both added and removed counts increase

No Changes

When texts are identical:

• All lines appear in gray
• Added and removed counts are zero
• Only unchanged count is positive

Understanding Diff Algorithms

The diff checker uses a line-by-line comparison algorithm that:

1. Splits text into lines for individual comparison
2. Matches identical lines and marks them unchanged
3. Detects additions when lines appear only in modified text
4. Detects deletions when lines appear only in original text
5. Handles reordering by looking for matching lines ahead

This approach works well for:

• Source code files
• Configuration files
• Text documents
• Log files
• Any line-based content

Diff vs Text Editor Comparison

Text Diff Checker (this tool):

• Line-by-line comparison
• Color-coded visualization
• Statistics summary
• Works in browser
• No installation needed

Text Editor Diff:

• May show character-level diffs
• Requires software installation
• Often more complex features
• File management integrated

When to use this tool:

• Quick comparisons
• Small to medium texts
• No software installation desired
• Need visual, color-coded output
• Want statistics at a glance

Frequently Asked Questions

Q: Does this tool support file uploads?

A: Currently, you need to paste text directly. Copy content from files and paste into the fields.

Q: Can I compare very large texts?

A: Yes, there is no size limit. However, very large texts may take longer to process.

Q: Why do I see more differences than expected?

A: Check for invisible characters, different line endings, or trailing spaces that may cause extra diffs.

Q: Can I save the comparison result?

A: You can copy the diff display or take a screenshot. The tool does not save comparisons.

Q: Does it work with code from different programming languages?

A: Yes, it works with any text including code from any programming language.

Q: Can I compare files with different line endings?

A: Yes, but different line endings (Windows vs Unix) may show as changes if not normalized.

Q: Is the comparison case-sensitive?

A: Yes, the comparison is case-sensitive. "Hello" and "hello" are considered different.

Privacy & Security

Your privacy is important to us:

• No data is sent to any server
• All comparison happens in your browser
• No cookies or tracking
• No account or login required
• Completely free to use

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