Code Compare & Diff Checker
Paste two versions of code or text to see every change highlighted, side by side or inline. It's built on Monaco, the editor inside VS Code.
- Runs on your device
- No sign-up
- Free, no watermark
How to use the Code Diff Checker
- 01Paste the original version on the left and the changed version on the right.
- 02Pick the language for syntax highlighting.
- 03Use the up and down arrows to jump between changes. The counter shows which one you're on.
- 04Press Copy to left or Copy to right to bring the current change across.
- 05Copy either side when you're done.
Good to know
Your code stays on your device
The comparison runs in your browser. The editor itself loads from a CDN, but your code is never sent.
24 languages
Syntax highlighting for JavaScript, TypeScript, Python, Java, Go, SQL, YAML and more, or plain text.
Edit and merge
Both sides are editable. Copy a single change from one side to the other.
Two views
Side by side, or inline with removed and added lines together.
Frequently asked questions
Is my code uploaded?
No. The diff is worked out in your browser. The page downloads the Monaco editor's own files from cdn.jsdelivr.net, but your code is never part of that or any other request.
Can I edit the text after pasting it?
Yes. In side-by-side view both sides are editable, and the highlighting updates as you type. Undo works as usual, including after Swap, Clear or a copied change.
What do Copy to left and Copy to right do?
They copy the current change, the one the counter points to, from one side to the other. That lets you merge changes one at a time.
Why does my phone show the inline view?
When the editor is too narrow for two columns, it shows the changes inline instead. Use a wider window to see them side by side.
How is this different from String Compare?
The Code Diff Checker compares line by line and suits files and code. String Compare works character by character and suits short strings such as keys or hashes.