Mono
Used by 3 peoplemono-project.com ↗

“Tombow MONO rubber eraser - Japanese erasers are a must have for illustrators.”
Shota Kotake Interview, Artist, art gallery technician · via Uses This 
“But once written there, the code runs for production on Ubuntu boxes again, using Mono.”
Rick Falkvinge Interview, Founder of the Swedish Pirate Party · via Uses This