textdiff / Privacy & about

Privacy & about

textdiff (formerly DiffText Pro) is a free set of text comparison tools. There are no accounts and no sign-up.

Your text stays in your browser

Every comparison on this site (text, code, JSON, YAML, XML, HTML, SQL, CSV, Excel, lists, strings, Word and PDF documents) runs as JavaScript inside your browser tab. Files you open are read locally. None of it is sent to our server to be compared.

The one exception: AI summaries, only when you click

On some tools there is a Summarise the changes with AI button. If you press it, the changed lines of your diff, with two unchanged lines of context around each change (up to 12,000 characters), are sent to our server and passed to an AI model (OpenAI's gpt-6-luna) through Vercel AI Gateway to write the summary. We don't store the text or the summary, and it isn't used to identify you. Our server keeps a short-lived count of requests per IP address to prevent abuse. If you never press the button, nothing is sent.

Remembering your text

If you tick "Remember my text on this device", your two texts and settings are saved in your browser's localStorage so they're still there next time. They never leave your device. Untick the box to erase them, or clear everything saved by this site here:

Clear all saved textdiff data

Share links

"Share link" compresses both texts into the part of the web address after the # sign. Browsers don't send that part to any server, so the comparison isn't stored by us; but anyone who has the link can read both texts, so share it only with people who should see them.

Analytics

We use Ahrefs Web Analytics to count page views. It is cookie-free and doesn't collect the text you compare.

How it works

Differences are computed with the Myers O(ND) algorithm via the open-source jsdiff library. Word documents are read with Mammoth, PDFs with Mozilla's PDF.js and Excel workbooks with read-excel-file, all in your browser. See how a diff checker works for an interactive walkthrough.