Diff Checker - Compare Text, Code & Files Online
Two versions of the same file - and you need to know exactly what changed before you commit, overwrite, or ship. Paste or upload both into this free online diff checker and get an immediate answer: a change count at the top, and every added, removed, and modified line highlighted in a side-by-side or unified view. Syntax highlighting covers 19 languages, from JavaScript and Python to SQL and YAML, and is set automatically for uploaded files. The comparison runs entirely in your browser - your text and code are never uploaded to a server.
How to Use the Diff Checker
1. Paste or upload both versions
.py upload is highlighted as Python, a .json upload as JSON). You can also pick the language from the dropdown at any time.2. Read the change count
The verdict appears above the editors as a summary such as 3 changes, 1 added, 1 removed. If both sides match, the tool says so outright - you run a diff check to confirm two files are identical without scanning a single line.
3. Pick a view
git diff output reads.4. Swap, clear, repeat
Swap flips the original and changed sides in one click - useful when you pasted them in the wrong order. Clear resets both editors for the next comparison, and fullscreen gives long files the whole screen.
Built for Code, Files, and Plain Text
- A code diff checker with real syntax highlighting. Compare code online with the formatting you'd see in your editor: 19 languages, including JavaScript, TypeScript, Python, Java, C#, Go, Rust, SQL, and YAML. Use it as a code difference checker during reviews - highlighted syntax makes a changed operator or renamed variable stand out in a way plain text never does.
- A file diff checker that reads your uploads. Upload any text-based file - source code, configs, logs, CSV, JSON, XML - and the language is detected from the file extension. No copy-pasting file contents into a text box first.
- A difference checker that keeps your content private. The diff runs entirely in your browser. Nothing you paste or upload is sent to a server, which makes it safe for proprietary code, credentials-adjacent configs, and unpublished drafts.
What Is a Diff Tool?
git diff does in a terminal, done in the browser with the differences highlighted. Developers use an online diff checker to review changes before a commit or after an AI tool rewrites a file; writers and editors use it to track revisions between drafts. This one adds a change count, syntax highlighting, and file uploads on top of the standard side-by-side comparison.FAQs
Split view shows the original and changed versions side by side in two columns. Unified view merges them into a single column, listing removed lines directly above their replacements - closer to how git diff output reads in a terminal.