Gaphor vs UMLet

Gaphor is a desktop modeling application for visualizing and documenting applications and systems with UML, SysML, RAAML, and C4. It implements a UML 2 data model and the UML, SysML, and RAAML OMG standards, and supports the C4 model. Its diagram options include Class, Interaction, State Machine, Block Definition, and Requirements diagrams, with diagram items that can be mixed and styled through a built-in engine. Diagrams export to SVG, PNG, PDF, or EPS, including batch export for every diagram in a model. Gaphor can also create a static, interactive, read-only HTML model report that needs no server or backend. As a Python library, it can inspect, generate, or update models through scripts or Jupyter notebooks; a Sphinx extension embeds diagrams in reStructuredText or Markdown documentation. The software is free under the Apache 2 license for Windows, macOS, and Linux. Windows users have installer, portable, and Winget options; macOS requires version 10.15 or newer.

UMLet is a free, open-source tool for quickly sketching UML diagrams, including class, use case, sequence, state, deployment, and activity diagrams. Users edit diagram elements by changing text in a small markup dialect rather than configuring pop-up dialogs. UMLet is available as a stand-alone desktop application, an Eclipse plugin, the browser app UMLetino, and a Visual Studio Code extension. The desktop application exports to BMP, EPS, GIF, JPG, PDF, PNG, and SVG, can copy diagrams to the clipboard, and supports command-line batch conversion of UXF files. UMLetino runs in a browser without installation, stores diagrams in browser storage, and exports PNG. Custom elements can be made with Java code that UMLet compiles on the fly, but only in the stand-alone version. The desktop application requires Java and runs on Java platforms such as Windows, Linux, and macOS. UMLet identifies its license as GNU GPL 3.0. It does not generate code from models or reverse-generate models from code; round-trip engineering is not planned.