Umple
Umple is a programming language that integrates UML modeling and code generation into one unified platform, allowing developers to seamlessly transition between design and implementation. It is primarily used for developing and maintaining large-scale object-oriented systems, particularly in domains such as software engineering, database modeling, and robotics.
Popularity: Less than 1% of developers are using or have used this language.*
*According to StackOverflow's 2023 survey.