Compare Text Without Upload

What "no upload" actually means

When you paste two texts here, they stay in the memory of the page you are looking at. The diffing algorithm — the same longest-common-subsequence logic that powers professional tools — runs in JavaScript on your own processor. There is no API call, no request body containing your text, and no log entry on a remote machine. The data has nowhere to go because the work never leaves the tab.

The same is true when you load files. The browser's FileReader hands the contents directly to the page, exactly as it would when previewing a photo before posting it — except here there is no post. The file is read locally and compared locally.

Why it matters

• Confidentiality — legal, medical, financial and HR documents must not be exposed to third-party services.
• Source code — proprietary logic, credentials and internal comments should never be pasted into a server you do not control.
• Compliance — many organisations forbid sending data to external processors, and a local tool keeps you on the right side of that policy.
• Trust — even with a reputable site, the safest data is the data that was never transmitted at all.

Verify it yourself

You do not have to take the claim on faith. Open your browser's developer tools, switch to the Network tab, and run a comparison — you will see no outbound request carrying your text. For an even simpler test, disconnect from the internet entirely: the tool keeps comparing without a hiccup, which is only possible because all the logic already lives in the page. A tool that needs the network to compare would stop working the moment you went offline.

Private but still full-featured

Privacy does not cost you capability here. You still get side-by-side and inline views, word and character level highlighting, options to ignore case, whitespace and blank lines, a similarity score, and unified diff export. Everything a server-backed comparator offers is available locally — the only thing missing is the upload.