katex_dart

A pure-Dart port of KaTeX. Parses LaTeX math into a backend-agnostic box tree and serializes it to SVG — with no Flutter dependency, so it runs in CLI, server, and web/SSR contexts. For a Flutter widget, see katex.

See demo at roszkowski.dev/katex.

Usage

import 'package:katex_dart/katex.dart';

void main() {
  // Primary API: a backend-agnostic box tree (height/depth/width in em).
  final box = renderToBox(r'\frac{a}{b}', options: const KatexOptions(displayMode: true));

  // Self-contained SVG (KaTeX fonts embedded via @font-face).
  final svg = renderToSvg(r'\sum_{i=0}^n i', options: const KatexOptions(displayMode: true));
}

See example/ for a complete runnable program.

CLI

dart run katex_dart "\frac{a}{b}" > out.svg
dart run katex_dart --display "\int_0^1 x^2\,dx" -o integral.svg

How it works

Lexer → MacroExpander → Parser → parse-node AST → builders → box tree → SVG. The box tree (BoxNode: GlyphNode, HBox, VList, RuleNode, SpanNode, SvgPathNode) is the primary public model — both the SVG serializer and the separate katex Flutter painter are pure consumers of it. Box dimensions are verified against original KaTeX (pinned 0.17.0).

Status

Covers a broad MVP of KaTeX (fractions, scripts, roots, big operators, delimiters, accents, fonts, environments, …). Full command/macro coverage and stretchy-glyph stacking are incremental.

License

MIT (this port) — see LICENSE. Ported from KaTeX (MIT). Bundled fonts are SIL OFL; see assets/fonts/OFL.txt.