Diff Checker
See exactly what changed between two versions of a text, file or config.
- Your data never leaves your device
- 100% free
- No sign-up
- Works offline after first load
How to compare two texts
- Paste or open the original and the changed text.
- Choose side by side or unified, line, word or character, and what to ignore.
- Jump between changes, then copy or download the diff.
About Diff Checker
Compare two texts, code files or configs side by side or unified.
Everything works in your browser, so it is instant and private, and your settings are remembered on this device.
Good for
- Code and config reviews
- Comparing API responses and JSON
- Checking document revisions
Tip: Format both JSON files with the JSON Formatter (with sorted keys) before comparing them.
Frequently asked questions
How do I compare two files?
Paste or open the original on the left and the changed version on the right — differences are highlighted instantly: removed in red, added in green, changed words marked inside each line.
Can it ignore whitespace changes?
Yes — ignore extra spaces, blank lines or upper / lower case so only real changes are shown.
Can I get a patch file?
Yes — download a unified .patch that git apply and patch understand, or an HTML report to share.
Which files can I open?
Any text or code file, plus Word, PDF and more — their text is extracted in your browser.
Is my data uploaded?
No. Everything is processed by JavaScript in your browser — nothing you paste or open is sent to a server, so it is safe for API responses, tokens, configs and customer data. It also works offline once the page has loaded.