Tool: Mermaid to ASCII art (mermaid-ascii)
Simon Willison’s Weblog
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16th July 2026
Tool
Mermaid to ASCII art (mermaid-ascii) — Convert Mermaid diagram syntax into ASCII and Unicode box-drawing art rendered entirely in your browser using a Go library compiled to WebAssembly. The tool supports flowcharts with labeled edges, subgraphs, and color definitions, as well as sequence diagrams with notes and control flow fragments, while offering customizable padding and output options.
After building the Mermaid to ASCII tool based on Grok Build's Rust code I learned that there's an older, more fully-featured Go library called AlexanderGrooff/mermaid-ascii that implements a similar pattern, so I had Claude Fable 5 compile that one to WebAssembly as well so I could compare the two.
This one includes support for colors!
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This is a beat by Simon Willison, posted on 16th July 2026.
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mermaid 4
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