There are many alternatives to ArgoUML for Mac and since it's discontinued a lot of people are looking for a replacement. The best Mac alternative is Dia, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to ArgoUML and 16 are available for Mac so hopefully you can find a suitable replacement. Other interesting Mac alternatives to ArgoUML are PlantUML (Free, Open Source), Visual Paradigm (Paid), Umbrello (Free, Open Source) and StarUML (Paid).
PlantUML is an open-source tool that uses simple textual descriptions to draw UML diagrams. The generator can be run anywhere within JVM and integrated with various application such as wiki, text editor, IDE, programming language, documentation generator, and others.
Visual Paradigm for UML (VP-UML) is a UML design tool and UML CASE tool designed to aid software development. VP-UML supports key modeling standards such as Unified Modeling Language (UML) 2.4, SysML, ERD, DFD, BPMN 2.0, ArchiMate 2.0, etc.
Umbrello is a Unified Modelling Language (UML) modelling tool and code generator. It can create diagrams of software and other systems in the industry-standard UML format, and can also generate code from UML diagrams in a variety of programming languages.
Violet is a UML editor with these benefits: Very easy to learn and use. Draws nice-looking diagrams. Completely free. Cross-platform. Violet is intended for developers, students, teachers, and authors who need to produce simple UML diagrams quickly.
BOUML is a free UML 2 tool box (under development) allowing you to specify and generate code in C++, Java, Idl, Php and Python. BOUML runs under Unix/Linux/Solaris, MacOS X(Power PC and Intel) and Windows.