Text Diff Checker

How to use Text Diff Checker

1. Open Text Diff Checker — it runs entirely in your browser with no setup.
2. Paste or type your input into the text area, or upload a file where supported.
3. Set any options you need. The result appears in the output panel — there is no upload step and no waiting on a server.
4. Review the output instantly; large inputs are handled locally without lag.
5. Copy the result to your clipboard or download it. Your data never leaves the page.

Why use Text Diff Checker?

• 100% free with no limits, no sign-up and no watermarks.
• Private by design — your data are processed in your browser and never uploaded to a server.
• Fast and lightweight, with instant results even on a phone or a slow connection.
• Works everywhere — any modern browser on Windows, macOS, Linux, Android or iOS.
• Part of a full text tools suite, so related text diff tasks are one click away.

What people use Text Diff Checker for

• Comparing two drafts to see what changed.
• Checking an edited document against the original.
• Finding the difference between two versions of a config or a message.

Text Diff Checker: limits and things worth knowing

• Differences are shown at word or line level, so a single changed word does not mark the whole line as different.
• Invisible differences are the ones this catches best — trailing whitespace, tabs versus spaces, and Windows CRLF against Unix LF line endings, none of which are visible in an editor.
• Reordered paragraphs show as a deletion plus an insertion, because a linear diff has no concept of a move.
• Both texts stay in your browser, which matters when comparing contract drafts or anything unpublished.

Is it private and secure?

Your privacy is built in. Text Diff Checker runs completely on your device, so whatever you enter stays in your browser and is never transmitted, logged or stored on any server.

Network activity: none. Nothing is sent and nothing is fetched. This tool makes no network request at all once the page has loaded — which is why it keeps working if your connection drops.

You do not have to take that on trust — our privacy proof page publishes the Content-Security-Policy that enforces it, lists every third party it permits, and shows how to verify the whole claim yourself.

Learn more

Is It Safe to Paste Production Data Into Online Tools? — JWTs, API responses and env files get pasted into online formatters every day. Here's what actually happens to that data and how to check before you paste.