Developer builds open-source AI diagram tool on Excalidraw to fix messy AI outputs

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A developer grew frustrated with AI tools like ChatGPT and Gemini producing broken or visually cluttered Mermaid diagrams and built an open-source alternative called OpenDiagram. The tool separates responsibilities: the AI determines system components while a deterministic layout engine handles placement, routing, and visual styling. OpenDiagram uses the Eclipse Layout Kernel to position nodes and a custom router to draw edges cleanly around boxes rather than through them. The output is rendered directly as editable Excalidraw elements, not static images or code blocks, allowing users to drag and adjust components freely. The project supports multiple diagram types including cloud architecture, sequence diagrams, and ER diagrams, with both sketch and classic visual themes.

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