Text Diff Checker

Compare two blocks of text instantly

The Text Diff Checker takes two blocks of text and highlights every difference between them line by line, so you can see exactly what was added, removed, or changed. It is ideal for spotting edits in a document, reviewing config changes, comparing two versions of a snippet, or catching a stray character that broke something. Instead of squinting at two windows side by side, you get a clear, colored breakdown of what differs.

How it works

The comparison runs locally in your browser using JavaScript. Paste your original text on one side and the modified text on the other, and the tool aligns the two and marks each differing line. Nothing is uploaded, so you can safely diff private notes, logs, or proprietary code without any of it leaving your device.

Practical use cases

• Review edits between two drafts of an article or email.
• Compare configuration files or environment variables before a deploy.
• Check what changed between two versions of a code snippet.
• Verify that copied text matches an original exactly.

For structured data, the JSON Diff understands objects and arrays instead of raw lines. To make bulk edits before comparing, try Find and Replace, and to clean up noisy input first, Remove Duplicate Lines can help normalize both sides.

Private by design

Because the diff is computed in-browser, no data is uploaded and nothing is stored. The tool is free, requires no account, and works on all modern browsers including mobile. Close the tab and both texts are gone for good.