fman
Compare files and folders using external tool inCompare files
Select two files or folders and run "Compare files" from the Command Palette.
Save to compare
Select one file or folder and run "Save to compare" from the Command Palette. Select another file or folder and run "Compare with saved" from the Command Palette.
External tools
When used first time it asks for a comparison tool. Any tool with command line interface which accepts two files or folders can be used. Example of comparison tools: KDiff3, WinMerge, Beyond Compare, or other (see this wiki article for more comparison tools).
Installation
Use fman's built-in command for installing plugins.