Visual Studio Code as a merge tool for Git Tower. Place both files to ~/Library/Application Support/com.fournova.Tower2/CompareTools/ and restart Git Tower

code.sh

 #!/bin/sh

code --wait $4

CompareTools.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" 
    "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<array>    
    <dict>
        <key>ApplicationIdentifier</key>
        <string>com.microsoft.VSCode</string>
        <key>ApplicationName</key>
        <string>Visual Studio Code</string>
        <key>DisplayName</key>
        <string>Visual Studio Code</string>
        <key>LaunchScript</key>
        <string>code.sh</string>
        <key>Identifier</key>
        <string>code</string>
        <key>SupportsMergeTool</key>
        <true/>
        <key>SupportsDiffChangeset</key>
        <false/>
    </dict>
</array>
</plist>

gitconfig

[merge]
        tool = vscode
[mergetool "vscode"]
        cmd = code --wait $MERGED

For windows follow this doc => https://www.git-tower.com/help/win/integration/custom-diff-tools