FastLaTeX

An embeddable, browser-based LaTeX editor with real-time PDF preview — Monaco editor, an in-browser pdfLaTeX engine (WASM), and PDF.js. Documents that need XeLaTeX or LuaLaTeX (fontspec, unicode-math, CJK, \directlua) are auto-detected; the full multi-engine pipeline runs through the headless compiler on the client or a Node server. TeX Live packages stream from a public CDN, so there's nothing to host.

Live Demo

Quick Start

FastLaTeX is not on npm — install from GitHub. The install ships a prebuilt lib/ bundle, so it works with no build step. monaco-editor and pdfjs-dist are peer dependencies.

npm install monaco-editor pdfjs-dist
npm install github:corca-ai/fastlatex#main

import * as pdfjsLib from 'pdfjs-dist'
import { FastLatex } from 'fastlatex'
import 'fastlatex/style.css'

// Worker setup is REQUIRED — see the Integration Guide for the full block.
self.MonacoEnvironment = { /* monaco workers */ }
pdfjsLib.GlobalWorkerOptions.workerSrc = new URL(
  'pdfjs-dist/build/pdf.worker.mjs', import.meta.url,
).toString()

const editor = new FastLatex('#editor', '#preview', {
  files: { 'main.tex': '\\documentclass{article}\\begin{document}Hi!\\end{document}' },
})
await editor.init()

👉 Start here: the Integration Guide has the complete worker setup and copy-pasteable recipes. A minimal example lives in examples/embed.html.

Packages / Entry Points

Import	Purpose
fastlatex	Full editor + PDF preview SDK.
fastlatex/headless	DOM-free compiler (your app owns editor/preview).
fastlatex/node	Run the engines under Node (installNodeWorkerHost + FastLatexCompiler).
fastlatex/lsp	Monaco-free LaTeX language service core.
fastlatex/lsp/monaco	Monaco provider adapter.
fastlatex/lsp/server	Transport-agnostic JSON-RPC language server.
fastlatex/style.css	Optional built-in UI/viewer styles.

Documentation

• Integration Guide — install, worker setup, headless, collaboration, engine selection.
• API Reference — constructor options, methods, events, PdfViewer.
• Architecture — SDK structure, VFS, LSP internals.
• Execution Model — client/server hybrid, pluggable per-stage backends.
• Engine & TeX Live — WASM engines, multi-engine routing, CDN.
• Bibliography · Warmup · Contributing

Contributing to FastLaTeX itself? See AGENTS.md and docs/develop.md.

Language features

The built-in LaTeX language server (editor-neutral cores in src/lsp/, with a Monaco adapter) provides:

Feature	Status
Completion (commands, refs, cites, packages, files)	✅
Hover (commands w/ signature + package, citations)	✅
Go-to-definition / references / rename	✅
Document symbols / outline	✅
Diagnostics + ChkTeX-style linter	✅
Signature help (argument hints)	✅
Folding ranges (environments, sections, % region)	✅
Document highlight (occurrences under cursor)	✅
Workspace symbols (labels/sections/commands)	✅ via fastlatex/lsp service + LSP server (Monaco has no workspace-symbol UI)
Code actions (insert ~, add \usepackage, create \label)	✅
Inlay hints (resolved .aux numbers next to \ref)	✅
Document links (\input/\include, \url/\href)	✅
Semantic tokens (commands, math, comments, verbatim)	✅
Formatting (latexindent-style)	⏳ planned

License

MIT