What is 3-Way Diff & Merge?
3-Way Diff & Merge is a free online tool for resolving conflicts between two different versions of a document by comparing them against a common base. It performs a line-based three-way merge, automatically accepting non-conflicting changes from either side and highlighting conflicts that require manual resolution. Perfect for merging code, configuration files, or any text content where two people have made independent edits.
Common Use Cases
Code Merging
Merge two branches of code changes against a common ancestor, resolving conflicts interactively.
Configuration Merging
Combine configuration file changes from multiple environments or team members.
Document Collaboration
Merge edits from two collaborators who independently modified the same document.
Version Conflict Resolution
Resolve version conflicts when syncing files across systems or repositories.
How to Use This Tool
- Paste the original (base) text into the Base panel
- Paste the first modified version into the Version A panel
- Paste the second modified version into the Version B panel
- Click Merge to compute the three-way diff and detect conflicts
- Resolve any conflicts using the Accept A, Accept B, or Accept Both buttons, then copy the merged result
Related Tools
Learn More
- Git Book — Branching & Merging Git's official documentation explains how three-way merges combine two diverging versions.