Diff Merger
3-way text merge: Base + Left + Right → merged output with conflict detection
Base (Original)
Left Version
Right Version
Merged Result
About the Three-Way Diff and Merge
This three-way merge tool compares a common base against two independently edited versions. Changes that touch different lines combine automatically, while genuine conflicts — the same line edited both ways — are flagged for you to resolve.
A three-way merge is what you need when two people edited the same document from the same starting point. A plain two-way comparison cannot tell you which side changed a line, because it has no record of what the line said originally.
Adding the base version resolves that. If only one side touched a line, that side's version is obviously the intended change and can be taken automatically. If both touched the same line differently, that is a real conflict requiring a human decision — and this is exactly the model git uses when it reports a merge conflict.
Useful beyond code: two reviewers editing the same policy document, a translation updated while the source also changed, or a config file modified on two servers. Everything runs in your browser.
How to use the Three-Way Diff and Merge
- Paste the base version. Provide the common original both copies started from.
- Paste the two edited versions. Add the left and right variants.
- Review the conflicts. Non-overlapping changes merge automatically; overlaps are flagged.
- Resolve and copy. Choose a side for each conflict and copy the merged result.
Three-Way Diff and Merge features
- Three-way merge
- Conflict resolution
- Multiple view modes
- Change highlighting
- Export merged result
- Version control
Frequently asked questions
How does diff merge work?
Compares two or three text versions, highlights differences, and helps merge changes into a final version.
Can I merge conflicting changes?
Yes! Shows conflicts and allows you to choose which changes to include in the merged result.
What comparison views are available?
Offers side-by-side, unified, and three-way comparison views for different merge scenarios.