Sequential Workflow Designer is a lightweight workflow designer
...Built entirely in TypeScript and rendered with SVG, it offers a fully generic and customizable platform for designing workflows, visual programming tools, or any other flow-based UI - independent of any specific workflow engine.
On-line examples: https://nocode-js.com/sequential-workflow-designer-examples
Documentation: https://nocode-js.com/
System dynamics program with additional features for economics
...Minsky is good for demonstrating mathematics too, with the most "math-like" interface in system dynamics.
Sign up to Minsky's Patreon page (for as little as $1 a month) at https://www.patreon.com/Ravelation/. This creates a user community, which SourceForge doesn't facilitate.