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Diff Checker
Paste the original on the left and the changed version on the right. Added lines are green, removed lines are red, and inside a changed line the words that differ are marked.
Loading Diff Checker…
Runs on your device. Nothing you paste is uploaded.
How to use the Diff Checker
- Paste or drop the original text into the left box and the changed text into the right.
- Choose side-by-side or inline, and whether to ignore whitespace or letter case.
- Select Compare. Step through the changes with the arrows, or download the result as a patch file.
Private by design
Plenty of online tools send what you paste to their server, which is a real risk with API keys, tokens and customer data. Diff Checker runs entirely in your browser: nothing is uploaded, logged or stored, and it keeps working with your network switched off. It’s free, with no account and no limits.
Questions
How does it decide what changed?
It finds the longest run of lines the two texts share (the same method as git diff) and reports everything else as added or removed. When a removed line is paired with an added one, the words that differ inside it are highlighted.
Can it compare files?
Drop a text file on either box: code, CSV, JSON, Markdown, logs. Word documents and PDFs aren’t plain text, so copy their text out first.
Is there a size limit?
Texts of tens of thousands of lines compare in about a second on a computer. Nothing is uploaded, so the limit is your device, not a server.
Is anything I paste sent to a server?
No. Every tool runs in your browser, so tokens, keys, customer data and code stay on your device. Once the page has loaded, the tools work offline too.
Do I need an account?
No. Every developer tool is free to use without signing in, with no limits.
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