About the Diff Checker
A diff checker compares two versions of text and shows exactly what changed. This free online Diff Checker highlights added and removed lines between an original and a changed version, so you can review edits at a glance.
It is ideal for comparing code, configuration files, drafts, or any two blocks of text. The comparison uses a line-level longest-common-subsequence algorithm and runs entirely in your browser — nothing is uploaded.
How to compare two texts
- Paste the original text into the left box.
- Paste the changed version into the right box.
- The differences are highlighted instantly below.
- Green lines were added; red lines were removed.
- Use Swap to reverse the comparison or Clear to start over.
Features
- Line-by-line comparison with added/removed highlighting.
- Added and removed line counts at a glance.
- Swap the two sides with one click.
- Works for code, config, prose, and any plain text.
- 100% client-side — your content never leaves your browser.
Diff Checker - Compare Text Online FAQs
What does the diff checker compare?
It compares the two texts line by line and marks which lines were added or removed to turn the original into the changed version.
Can I compare code?
Yes. The tool works with any plain text, including source code and configuration files. Whitespace and indentation are compared exactly.
Is my data uploaded anywhere?
No. The comparison runs entirely in your browser using JavaScript. Your text is never sent to or stored on a server.
What do the colors mean?
Green lines exist only in the changed version (added), red lines exist only in the original (removed), and unmarked lines are unchanged.
Is the diff checker free?
Yes, it is completely free with no signup and no limits.
