diff3
The same merge as git
Uses the diff3 algorithm behind git and other version control tools, so you get the same automatic merges and the same conflicts.
Three-Way Merge · diff3 · Free
Merge two versions. Resolve only what clashes.
Give us the original and two edited copies. Changes on one side merge automatically — you decide the rest with one click.
your version
common ancestor
their version
The merged result appears here.
Paste three versions to merge them
Changes made on only one side are merged automatically. Where both sides changed the same lines, you pick the outcome — nothing is uploaded.
Unresolved conflicts are written with git-style <<<<<<< markers when you copy or download.
How It Works
Three steps. No sign-up.
- 1
Paste the original file as Base, your edited copy as Mine, and the other edited copy as Theirs. You can also drop files on each pane.
- 2
Press Merge. Lines changed on only one side are merged automatically; lines both sides changed differently become conflicts.
- 3
Pick Mine, Theirs, Both or edit each conflict by hand, then copy or download the merged file. Unresolved conflicts keep git-style markers.
Features
Built for real-world data.
Auto
Safe changes merge themselves
Edits made on only one side — or identically on both — are applied automatically and labelled with where they came from.
Resolve
One click per conflict
Use Mine, Use Theirs, keep both in either order, keep Base, or edit the result by hand. Undo any choice.
Words
See exactly what clashes
Conflicting lines are shown side by side with the differing words highlighted, and the Base version one click away.
Markers
Git-compatible output
Anything you leave unresolved is written with <<<<<<<, ||||||| and >>>>>>> markers, ready to finish in your editor.
Private
Nothing is uploaded
Config files, contracts and source code are merged entirely in your browser. Share links keep the content in the URL fragment.
FAQ
Questions & answers
What is a three-way merge?
A three-way merge combines two edited copies of a file using the original they both started from (the base). Knowing the base tells the merge which side changed each line, so one-sided edits can be applied automatically and only real clashes need a decision.
What counts as a conflict?
A conflict happens when both versions changed the same lines — or lines right next to each other — in different ways. If both sides made the exact same change, it merges automatically.
What if I don’t have the base version?
Leave Base empty and every difference between Mine and Theirs becomes a conflict for you to resolve — effectively a guided two-way merge.
Can I use it to resolve a git merge conflict?
Yes. Use git show :1:file for the base, :2:file for yours and :3:file for theirs, paste them in, resolve, then copy the result back into the file.
Are my files uploaded?
No. The merge runs entirely in your browser. History is stored only on your device, and share links carry the text inside the link itself.
Can it ignore indentation changes?
Yes. Turn on “Ignore whitespace changes” so re-indented lines don’t cause conflicts with real edits on the other side.
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