Are my files uploaded?

No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.

Is it free? Are there limits or watermarks?

Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.

Does it work offline?

Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.

Home / Text & Data / Diff Checker

Diff Checker

Compare text and code side-by-side or inline.

Free, no uploads, no sign-up. Runs 100% in your browser.

How Diff Checker works

Diff Checker runs entirely in your browser. Compare text and code side-by-side or inline. Under the hood it uses jsdiff (the Myers diff algorithm for line, word and character differences). Your files are read into this tab’s memory, processed on your own CPU, and handed back to you as a download. Nothing is sent to a server.

How to use Diff Checker

Open Diff Checker and paste your text.
Choose an operation or option.
Review the live result.
Copy it or download it.

Tips

Text never leaves your device, so it is safe for drafts and private notes.

Diff Checker FAQ

Are my files uploaded?: No. This tool runs entirely in your browser tab. Files are read from your disk into memory and the result is generated locally.
Is it free? Are there limits or watermarks?: Free and open source (MIT). There are no file-size caps, daily quotas, accounts or watermarks.
Does it work offline?: Yes, once the page (and any engine it needs) has loaded, it keeps working without a connection thanks to the service worker cache.

Related tools

Compare PDF: Side-by-side text diff of two PDF versions.
Text Cleaner: Remove duplicates, sort lines, trim spaces and strip line breaks.
Word Counter: Words, characters, sentences, reading time and keyword density.
Time Zone Converter: Convert times across zones, keep a world clock and find meeting times that suit everyone.