Lot of companies are moving away from UML but not away from modeling tools by using domain specific languages (DSL) instead of a language like UML which tries to please everybody. The Eclipse Foundation hosts lot of domain specific tools like Xtext (1) for textual DSL or Sirius (2) for graphical DSL. Both tools are even compatible since they are using the same underlying framework, the Eclipse Modeling Framework (EMF). With those tools, and others (have a look at all the modeling tools in the Eclipse Foundation), you can build a "development environment" for your own domain with your dedicated editors (syntax highlighting, completion, error detection, etc) and designers.

1: https://www.eclipse.org/Xtext/ 2: http://www.eclipse.org/sirius/

Disclaimer: I work for the company behind Eclipse Sirius.