Text Diff Checker
Compare two blocks of text line by line and instantly see what was added, removed, or left unchanged.
🔒 Processed locally in your browser
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How to use
- Paste or type your original text into the "Original" box on the left (or top, on mobile).
- Paste or type your changed text into the "Changed" box on the right (or below it, on mobile).
- The diff result updates live underneath as soon as either box changes — there's no button to press.
- Added lines are highlighted in green with a + prefix, removed lines in red with a - prefix, and unchanged lines are shown in the default color.
Features
- Line-by-line diff with clear, easy-to-scan color coding
- Updates live as you type or paste — no button to press
- Shows a running summary count of lines added and removed
- 100% client-side — your text never leaves your browser
- Works with code, prose, config files, or any plain text
Frequently asked questions
Does my text get uploaded anywhere?
No. Text Diff Checker runs entirely in your browser — both blocks of text are compared locally and are never sent to a server.
Does it diff word-by-word or line-by-line?
Line-by-line only. A line is considered changed if it isn't identical to a line in the other text — the tool doesn't highlight the specific words that differ within a line. That's an honest current limitation, not a bug.
Is there a limit to how much text I can compare?
Yes. There's a practical limit of a few thousand lines per side (around 5,000) to keep the browser responsive, since the diff algorithm's cost grows with the length of both texts.
Is whitespace significant?
Yes. Trailing or leading whitespace differences will cause a line to show up as changed. This is intentional, so the comparison stays exact.
Can I diff source code files?
Yes. The tool works on any plain text, including source code, configuration files, or logs — though it doesn't apply syntax highlighting.