BESSER vs kUML
BESSER
besser-pearl.orgkUML
kuml.devSide by side
| Figure | BESSER | kUML |
|---|---|---|
| Price from | Free | Free |
| Free plan | Yes | Yes |
| Free trial | — | — |
| Open source | Yes | — |
| Web | Yes | Yes |
| Windows | Yes | Yes |
| macOS | Yes | Yes |
| Linux | Yes | Yes |
| API | Yes | Yes |
| Self-hosted | Yes | Yes |
| Plans published | 2 | 1 |
| Spec score · UML Modeling Software | 9.0 (#1) | 7.8 (#14) |
| Integrations | Documented generation targets include Python, FastAPI, Django, SQLAlchemy, SQL, Java, React, PyTorch and TensorFlow. | The project lists CLI, Gradle, IntelliJ, Obsidian, Asciidoctor, and VS Code integrations. |
| License | BESSER is open source under the MIT license. | The project is licensed under Apache 2.0. |
| Security | For the Spec-Driven Agent free tier, no API key is required, and any user-supplied key is never stored. | The MCP authoring server validates scripts with KumlScriptGuard before evaluation, using the same sandboxing applied by the CLI render and validate commands. |
| What it does | BESSER is an open-source low-code platform that turns models into APIs, databases, agents and deployment artifacts. | kUML expresses UML 2.x, SysML 2, C4, BPMN 2.0 and ERM as a type-safe Kotlin DSL. |
Plans
In their own words
BESSER
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.
kUML
kUML is a modeling tool that expresses UML 2.x, SysML 2, C4, BPMN 2.0, and ERM as a type-safe Kotlin DSL. It supports all 14 UML 2.x diagram types, with compile-time validation and IDE support. Built-in transformations generate JPA, OpenAPI 3.0 YAML, Kubernetes manifests, and Dockerfiles. Integrations include CLI, Gradle, IntelliJ, Obsidian, Asciidoctor, and VS Code. For interoperability, it supports Structurizr DSL round-tripping and optional XMI through the kuml-io-emf module. kUML also includes an MCP server for agent introspection and a kuml ai subcommand for AI-assisted modeling. It is free and open source under Apache 2.0, with no paid plans or feature limits stated. It runs on Windows, macOS, Linux, and the web, and can be deployed both self-hosted and through other means. Install options include packages for major desktop systems, Docker, and Maven Central library modules. Rendering Kotlin scripts executes their source code, so use only scripts or workspaces you trust.