When you’re refactoring code, revising documentation, or reviewing content, it makes a big difference to see exactly what has changed between two versions. The Text Diff Checker is a lightweight, browser-based diff viewer that highlights additions, deletions, and unchanged lines side by side.

What this tool does

• Compares two blocks of text or code (for example, before and after a refactor).
• Computes a line-by-line diff and clearly marks added, removed, and unchanged lines.
• Displays both versions side by side, making it easy to scan through edits visually.

How to use it

1. Paste the original text into the Left (Original) box.
2. Paste the new or updated text into the Right (Modified) box.
3. Click Compare to generate a visual diff.
4. Scroll through the result to see added lines in green, removed lines in red, and unchanged lines in neutral colors.

All diff calculations run locally in your browser, so your content never leaves the page.

For very large inputs, the tool automatically stops rendering diffs once the comparison would become too heavy for the browser and shows a clear warning instead.