Diff Merger

Merge two texts side by side online for free. Pick changes from either version and resolve conflicts visually. No signup.

Runs entirely in your browser — files never uploaded

Version A

Version B

How to use Diff Merger

1. Paste both versions. Enter the original text in Version A and the modified text in Version B.
2. Compare and resolve. Click Merge to see a line-by-line diff. For each conflict, click Use A or Use B to pick the version you want.
3. Copy the merged result. Once you're happy with the choices, copy the merged text or download it as a file.

How does the diff algorithm work?

It performs a simple line-by-line comparison. Lines that match stay in the output; lines that differ are presented as conflicts for you to resolve.

Can I merge binary files?

No, this tool works with plain text only. For binary files, use a dedicated merge tool like Git.

Is there a size limit?

There's no hard limit, but very large texts (10,000+ lines) may slow down your browser.

Is my data sent to a server?

No. The diff and merge happen entirely in your browser. Nothing is uploaded.

Can I undo my choices?

Yes — click the opposite button (Use A / Use B) on any conflict line to switch your selection at any time before copying.