Mermaid diagrams without the Chromium tax

What it does Pretty Mermaid is a skill for AI coding agents—Claude Code, Cursor, Codex, and others—that turns plain-text Mermaid diagrams into polished SVGs or ANSI-colored ASCII art. It runs entirely inside Node.js without calling out to Chromium, Puppeteer, or any DOM, which means it works offline and inside headless environments. You get fifteen themes, six diagram types, and batch parallel rendering in a package that behaves more like a native CLI tool than a web service.

The interesting bit Most Mermaid renderers eventually call a browser; this one doesn’t. The project recognizes that AI agents spend their lives in terminals, so it offers both publication-ready SVGs and rough-and-ready ASCII output for the same source file. It is essentially a curated, agent-friendly distribution of the beautiful-mermaid renderer wrapped in a skill format with theming and batching baked in.

Key highlights

• Runs fully offline with no Chromium, Puppeteer, or DOM dependency
• Dual-output: themed SVGs for documentation and ANSI-colored ASCII for terminal sessions
• Fifteen built-in themes including Catppuccin, Tokyo Night, Nord, and GitHub variants
• Supports six diagram types: flowchart, sequence, state, class, ER, and XY charts
• Handles CJK text, multiline labels, configurable ELK layout spacing, and batch parallel rendering

Verdict Useful if you want AI agents to draw diagrams inside terminal sessions and export polished SVGs in the same breath. Pass if your Mermaid pipeline already depends on browser-specific features or you rarely touch the command line.