Diff Checker
Compare two texts and see what changed
Paste both versions below. Green means added, red means removed. Your text never leaves the browser — there’s no upload and no account.
Upload first file
or click to pick a file
Supported formats: .txt, .json, .csv, .xml, .yaml, .yml, .md
Maximum size: 5MB
Upload second file
or click to pick a file
Supported formats: .txt, .json, .csv, .xml, .yaml, .yml, .md
Maximum size: 5MB
Tip: press Ctrl+Enter to compare right away
Reading the result
The two panels stay aligned line for line. A red highlight on the left marks something the original had and the new version dropped; a green highlight on the right marks what the new version introduced. When a line was edited rather than replaced, you’ll see both — the old text struck through on the left, the replacement on the right.
Switch between line and wordmode depending on what you’re looking for. Line mode is the right default for code and configuration, where a whole line usually changes at once. Word mode earns its keep in prose: reword half a sentence and line mode paints the entire paragraph red, while word mode points at the four words you actually touched.
When whitespace lies to you
Reindent a file, convert tabs to spaces, or let an editor strip trailing blanks and a diff will happily report that every single line changed. That’s technically true and completely useless. Tick Ignore whitespace and the comparison looks past it, leaving only the edits that carry meaning. The same goes for Ignore casewhen you’re chasing a content change through text that also got recapitalised.
Nothing gets uploaded
The comparison runs in your browser, in JavaScript, on your machine. No copy of your text is sent to a server, stored, or logged — which matters when the two things you’re comparing happen to be a contract draft, a patient record, or an API key that leaked into a config file. Large inputs get handed to a Web Worker so the page stays responsive, but they don’t travel any further than that.
Comparing something more specific?
Plain text comparison treats every character the same way. That’s the wrong tool when the format has structure of its own, so there’s a dedicated version for each of these:
- Code diff — Syntax highlighting for 22 languages, so a moved brace doesn't read as a rewrite.
- JSON diff — Compares structure instead of characters — key order stops mattering.
- CSV diff — Detects the delimiter and marks the individual cells that changed.
- XML diff — Walks the tree, so you see which attribute moved and where.
- Markdown diff — Shows the source and the rendered result side by side.
Those pages are in Czech, but the tools themselves work the same way and need no reading to operate.