Code review
Check a patch before you push it, or compare a teammate's file against the version you have locally.
Code diff
Compare code files online, free and private
A line-by-line source diff for reviews, merge conflicts and config drift. Upload two files or paste them in, toggle whitespace handling, and read the change set.
Base version
Changed version
Everything is compared in your browser. No text or file ever leaves this device.
Paste your original text on the left, the revised version on the right, then press Compare.
Config drift
Diff two .env, YAML or Dockerfile variants to find the one line that differs between staging and production.
Merge conflicts
Drop both sides of a conflict into the panes and see the real difference without the marker noise.
Frequently asked questions
- How do I compare two code files online for free?
- Paste each version into a pane or upload the two files. Redline diffs them line by line in your browser and marks added lines green and removed lines red.
- Which languages are supported?
- Any plain-text source: JavaScript, TypeScript, Python, Go, Rust, Java, C/C++, SQL, shell, YAML, and more. The diff is language-agnostic and works on config files too.
- Can I ignore indentation changes?
- Turn on Ignore whitespace to hide reformatting noise and show only real logic changes.
- Is my source code sent anywhere?
- No. The comparison happens entirely on your device — nothing is transmitted, logged, or stored.