Line diffs for code reviews
A line-oriented diff focuses attention on insertions and deletions instead of re-reading entire files. Keep snippets reasonably sized for the clearest result in the browser.
Code Diff
Paste two code versions to highlight what changed line by line—useful for reviews, patches, and config tweaks.
Original code
New code
How it works
- 1
Paste the original content on the left (or first panel).
- 2
Paste the changed content on the right (or second panel).
- 3
Review the highlighted differences; copy a unified view if offered.
Why use this tool
- Runs entirely in your browser — nothing is uploaded to a server.
- 100% free, no sign-up, no limits.
- Works in any modern browser — no app install, no extension, no account.
How to use Code Diff
Use both panels in Code Diff to compare two versions. Differences update as you edit either side — nothing needs to be uploaded.
Tips for better results
Keep formatting consistent when comparing code. For huge files, compare a focused slice first.
Privacy and offline-friendly processing
Whenever possible, Code Diff processes your data locally with JavaScript in this page. That means drafts, secrets, and unfinished work stay on your device by default. Prefer this workflow when you do not want to upload sensitive text, tokens, passwords, or files to a third-party service.
Frequently asked questions
Does this understand programming language syntax?
No. It compares lines of text, so it works for any language or plain config files.
Is my code uploaded?
No. Diffing runs entirely client-side.
Is my data uploaded when I use this tool?
For most FlyUtils tools, no. Processing happens in your browser with JavaScript. If a tool ever needs a server, that will be stated clearly on the page.
Is Code Diff free to use?
Yes. Code Diff is free, with no sign-up and no artificial usage caps for normal personal and work use.
Does Code Diff work on mobile?
Yes. The page is mobile-first, so you can paste input, tweak options, and copy results from a phone or tablet.