Round Robin Generators - Pickleball

Websites

https://jumbleddoubles.com/

Spreadsheets with 8-18 player

iPhone Apps

PB Play

This one is fairly basic and fairly inexpensive.  If you have 12 players on 2 courts, the same 4 will always sit together.

Round Robin Assistant

This one is more expensive but has many more features.  You can do Mixed Doubles, Gender Doubles, regular round robins etc.

Android Apps

Doubles Match Maker