Pele is a from-scratch reimplementation of Mermaid diagram rendering that outputs SVG directly, skips the entire Mermaid.js runtime, and themes via CSS custom properties. It supports every diagram type in Mermaid 12.1.0. The pitch is simple: same syntax, radically smaller and faster output. The numbers are the story. Bundle size drops from 1.6 MB gzipped to 230 kB — roughly 7× smaller. Render time drops from 6–82 ms to 0.05–0.3 ms, which at the extremes is a 500× improvement. Mermaid.js ships 23 direct dependencies; Pele ships zero. These are not incremental gains. This is a ground-up rethink of what a diagram renderer needs to be. The theming model is where Pele makes its most opinionated move. Mermaid uses theme configuration objects — you pick a preset or write JSON. Pele uses CSS variables. You set --pele-bg, --pele-fg, --pele-line, and the diagrams inherit your page's visual language without re-rendering. For anyone who has wrestled with Mermaid theme overrides inside a design system, this is the correct answer to the wrong abstraction. The API is minimal to the point of bluntness. npm install pele, import render, pass it a Mermaid string, get back an SVG string. Insert it into the DOM. That's it. No init lifecycle, no runtime parsing step, no async rendering pipeline. This is a pure function that takes text and returns markup. Pele was built for Obsidian, the note-taking app, where diagram rendering speed directly affects editing feel and where theme consistency matters because users customize everything. That origin explains the design constraints: it had to be fast enough to render inline during typing, small enough not to bloat a desktop app, and themeable enough to match any vault's CSS. Those constraints produced something more general than its origin. The tradeoff is compatibility surface. Pele claims full Mermaid 12.1.0 syntax support, but the real test is edge cases — unusual diagram types, complex nested subgraphs, and the long tail of syntax that users have come to rely on in Mermaid.js. The project links to a compatibility page comparing syntax, layout, and features, which suggests the authors know this is the battleground. Pele is open source and named after the Hawaiian goddess of volcanoes and fire, which is the kind of naming energy you get from a project that knows it's picking a fight with an incumbent.
