Show HN: Mermaid Formatter – CLI and library to auto-format Mermaid diagrams

1 point

4 months ago

I built a zero-dependency formatter for Mermaid diagram syntax. It normalizes indentation, whitespace, and arrow spacing across all diagram types.

Features: - CLI tool (mermaidfmt) with stdin/file/in-place support - Programmatic API for integration (e.g. format Mermaid blocks in Markdown) - Nested block indentation (alt/loop/par/subgraph track depth) - Context-aware parsing (else only inside alt, and only inside par) - Arrow normalization: A->>B:msg → A ->> B: msg

npm install -g mermaid-formatter