BESSER vs Violet UML Editor

BESSER is an open-source low-code platform for building smart applications by modeling once and generating APIs, databases, agents, and deployments. Its 15+ generators cover databases, REST APIs, web apps, AI agents, and deployment manifests. Built-in modeling includes class diagrams, state machines, object diagrams, agents, and deployment specifications. The GUI Creator deterministically generates complete React frontends from platform-independent GUI models, and AI-assisted modeling supports software with embedded AI components. BESSER connects through an MCP server to Claude Desktop, Cursor, and other MCP-aware clients; BESSER Skills also integrate with Claude Code, Cursor, and Copilot for model and code-generation workflows. Generated Docker components can be used to deploy a running application from a model. The project is MIT-licensed and free, with no freemium tier or hidden fees. It runs on the web, Linux, macOS, and Windows. The Python package installs with pip, and the full codebase can run locally for extensions and generators. It is tested on Python 3.10, 3.11, and 3.12; Python 3.13 is not supported yet. Support includes an on-page assistant, email, and weekly GitHub bug triage.

Violet UML Editor is a free, open-source application for drawing simple UML diagrams quickly. It supports class, activity, object, sequence, state and use case diagrams. The project describes Violet as easy to learn and use, and intended for developers, students, teachers and authors who need straightforward UML diagrams. Violet is licensed under GNU General Public License version 2.0 (GPLv2) and is written in Java, with Java Swing and Java SWT listed as interfaces. Linux, Mac and Windows are named operating systems, while the platform listing also includes web. The source repository directs users to SourceForge for downloads. Building from source requires Java Development Kit 17 or greater and Maven 3 or greater; the repository specifies running `mvn clean package` from the root directory to compile and package the project. The maintainer invites contributors to submit pull requests and says requests will be examined before contacting contributors. Violet has one listed plan: free, described as a completely free, cross-platform UML editor. Deployment is listed as both, with web, Windows and Linux among supported platforms.