tecgonic

A Go library that compiles LaTeX documents to PDF using the Tectonic engine compiled to WebAssembly. No native TeX installation required.

Features

• Pure Go — the Tectonic engine runs as WASM via wazero (no CGo)
• Self-contained bundle download — fetches the TeX Live bundle on first use
• Concurrent compilation — each Compile call gets its own isolated WASM instance
• WASM compilation cache — optional on-disk cache cuts startup from ~1.4 s to ~50 ms

Quick start

package main

import (
	"context"
	"os"

	"github.com/mgilbir/tecgonic"
)

func main() {
	ctx := context.Background()
	bundleDir := os.Getenv("HOME") + "/.cache/tecgonic/bundle"
	cacheDir := os.Getenv("HOME") + "/.cache/tecgonic/wasm-cache"

	// Download the TeX bundle (~800 MB, one-time).
	tecgonic.PrepareBundle(ctx, bundleDir, "", false, tecgonic.WithProgress(os.Stderr))

	// Create compiler and generate format file (one-time).
	compiler, _ := tecgonic.New(ctx,
		tecgonic.WithDefaultBundleDir(bundleDir),
		tecgonic.WithCompilationCache(cacheDir),
	)
	defer compiler.Close(ctx)
	compiler.GenerateFormat(ctx, bundleDir)

	// Compile LaTeX to PDF.
	pdf, _ := compiler.Compile(ctx, []byte(`\documentclass{article}
\begin{document}
Hello, World!
\end{document}
`))
	os.WriteFile("output.pdf", pdf, 0o644)
}

See examples/simple for a complete runnable example.

WASM compilation cache

Creating a Compiler with New() involves compiling the Tectonic WASM module, which takes ~1.4 s. Pass WithCompilationCache(dir) to cache the compiled module on disk. Subsequent calls load the cached result in ~50 ms — a ~26x speedup.

compiler, err := tecgonic.New(ctx,
	tecgonic.WithDefaultBundleDir(bundleDir),
	tecgonic.WithCompilationCache("/path/to/cache"),
)

Benchmark results (AMD Ryzen 9 6900HX):

BenchmarkNew/NoCache       1   1360 ms/op   79 MB/op   117k allocs/op
BenchmarkNew/WithCache    22     51 ms/op  6.8 MB/op    31k allocs/op

The cache directory can be shared across processes. The first invocation populates the cache; all later invocations (including from different processes) read from it.

Building the WASM module

The pre-built WASM artifact is included under wasm/. To rebuild it from the Tectonic source:

make wasm

This uses Docker to cross-compile Tectonic to wasm32-wasip1. See the Dockerfile for details.

Thanks

This project would not be possible without:

• Tectonic — a modernized, complete, self-contained TeX/LaTeX engine. Tectonic does all the heavy lifting of turning LaTeX into PDF; tecgonic simply makes it callable from Go.
• wazero — a zero-dependency WebAssembly runtime for Go. wazero makes it practical to embed the Tectonic WASM binary in a pure-Go library with no CGo and no external dependencies.