Can I compare source code files like JavaScript, Python, or HTML?

Yes. The diff checker works with any plain text formatting including programming source code, configuration files, JSON, markdown, and prose.

Does this tool detect whitespace and indentation differences?

Yes. Strict line comparison preserves spaces, tabs, and line breaks, ensuring precise identification of formatting adjustments.

Can I copy the diff results for documentation?

Yes. Use the Copy Diff Patch button to export the unified comparison results directly to your clipboard.

Is my confidential source code uploaded to any server?

No. All comparison calculations run exclusively in your browser memory without network communication.

Text Diff Checker

Runs in Browser

Compare two text documents side-by-side to highlight added and removed lines.

How to Use the Text Diff Checker

Paste your original text version into the left input container.

Paste your modified text version into the right input container.

Review the live summary statistics showing the count of added lines, removed lines, and match status.

Examine the unified diff viewer below to see color-coded additions in green and deletions in red.

Click Copy Diff Patch to copy standard unified patch formatting to your clipboard.

Understanding Text Diff Checker

In software engineering, content editing, legal contract review, and document publishing, tracking precise changes between text iterations is an indispensable requirement. Discovering a minute modification or identifying unintended line deletions within thousands of words is nearly impossible with manual proofreading. Our Text Diff Checker provides a high-performance visual comparison engine built right into your browser. Utilizing an efficient dynamic programming implementation of the Longest Common Subsequence (LCS) algorithm, the tool compares original and updated versions to pinpoint line additions, deletions, and unchanged segments with complete mathematical rigor. Key benefits of our diffing suite: 1. **Unified Line-by-Line Presentation:** Color-coded green highlights indicate added content, while red highlights clearly display deleted lines, complete with dual line numbers for fast reference. 2. **Instant Real-Time Execution:** As you type or paste modifications into either textarea, the diff calculation updates instantaneously without manual submission. 3. **Comprehensive Metric Counter:** Instantly know the total quantity of modified lines, additions, and deletions at a glance. 4. **Git-Compatible Patch Output:** One-click copy option exports your diff in clean, standard patch notation suitable for engineering logs, issue tickets, or documentation updates. 5. **Absolute Privacy:** Sensitive legal agreements, financial records, and confidential source code never get transmitted to third-party cloud servers. Every single character comparison takes place strictly within your local machine.