diffmerge

Install command: 
brew install --cask diffmerge

Name: DiffMerge

Visually compare and merge files

https://www.sourcegear.com/diffmerge/

Cask JSON API: /api/cask/diffmerge.json

Cask code: diffmerge.rb on GitHub

Current version: 4.2.1.1013

Current version requires: macOS >= 10.11

diffmerge is built for Intel macOS and so requires Rosetta 2 to be installed.
You can install Rosetta 2 with:
    softwareupdate --install-rosetta --agree-to-license
Note that it is very difficult to remove Rosetta 2 once it is installed.

Analytics:

Installs (30 days)
diffmerge 406
Installs (90 days)
diffmerge 1,226
Installs (365 days)
diffmerge 4,265
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