Using All Four LaTeX Engines via the FormaTeX API

curl -X POST https://api.formatex.io/api/v1/compile \
  -H "X-API-Key: $FORMATEX_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "engine": "pdflatex",
    "content": "\\documentclass{article}\\usepackage[utf8]{inputenc}\\usepackage{amsmath}\\begin{document}\\section{Introduction}The Pythagorean theorem: $a^2 + b^2 = c^2$.\\end{document}"
  }' \
  --output pdflatex-output.pdf

\documentclass{article}
\usepackage{fontspec}
\setmainfont{TeX Gyre Termes}      % Times New Roman compatible
\setsansfont{TeX Gyre Heros}       % Helvetica compatible
\setmonofont{JetBrains Mono}       % any system monospace font

\begin{document}
\section{Custom Fonts}
This document uses OpenType fonts directly via fontspec.
No encoding packages needed — XeLaTeX handles Unicode natively.

\textbf{Bold}, \textit{italic}, and \texttt{monospace} all
render with proper OpenType features including ligatures.

Arabic: \textrm{مرحبا} \quad Hebrew: \textrm{שלום}
\end{document}

curl -X POST https://api.formatex.io/api/v1/compile \
  -H "X-API-Key: $FORMATEX_KEY" \
  -H "Content-Type: application/json" \
  -d "{\"engine\": \"xelatex\", \"content\": $(cat xelatex-doc.tex | jq -Rs .)}" \
  --output xelatex-output.pdf

\documentclass{article}
\usepackage{fontspec}
\usepackage{luacode}

\begin{document}

\section{Lua-Generated Content}

The following multiplication table was generated by Lua code
running inside the LaTeX document:

\begin{center}
\begin{tabular}{r|rrrrr}
$\times$ & 1 & 2 & 3 & 4 & 5 \\
\hline
\directlua{
  for i = 1, 5 do
    tex.sprint(i)
    for j = 1, 5 do
      tex.sprint(" & " .. (i * j))
    end
    tex.sprint(" \\\\")
  end
}
\end{tabular}
\end{center}

\section{Dynamic Text}

\directlua{
  local words = {"alpha", "beta", "gamma", "delta"}
  for i, w in ipairs(words) do
    tex.sprint(i .. ". " .. w:upper() .. " ")
  end
}

\end{document}

curl -X POST https://api.formatex.io/api/v1/compile \
  -H "X-API-Key: $FORMATEX_KEY" \
  -H "Content-Type: application/json" \
  -d "{\"engine\": \"lualatex\", \"content\": $(cat lualatex-doc.tex | jq -Rs .)}" \
  --output lualatex-output.pdf

\documentclass{article}
\usepackage{amsmath}
\usepackage[backend=bibtex]{biblatex}

% Embed the .bib inline for single-file API calls
\begin{filecontents*}{refs.bib}
@book{knuth1984tex,
  author    = {Knuth, Donald E.},
  title     = {The {\TeX} Book},
  publisher = {Addison-Wesley},
  year      = {1984}
}
@article{lamport1994latex,
  author  = {Lamport, Leslie},
  title   = {{\LaTeX}: A Document Preparation System},
  year    = {1994},
  publisher = {Addison-Wesley}
}
\end{filecontents*}

\addbibresource{refs.bib}

\begin{document}

\section{Introduction}

TeX was created by \textcite{knuth1984tex} to produce
high-quality mathematical typography. \LaTeX{} \cite{lamport1994latex}
provides a higher-level document preparation system on top of TeX.

\printbibliography

\end{document}

curl -X POST https://api.formatex.io/api/v1/compile \
  -H "X-API-Key: $FORMATEX_KEY" \
  -H "Content-Type: application/json" \
  -d "{\"engine\": \"latexmk\", \"content\": $(cat bibliography-doc.tex | jq -Rs .)}" \
  --output bibliography-output.pdf

type Engine = "pdflatex" | "xelatex" | "lualatex" | "latexmk";

function detectEngine(latexSource: string): Engine {
  // Bibliography → must use latexmk
  if (/\\bibliography\{|\\addbibresource\{/.test(latexSource)) {
    return "latexmk";
  }

  // Lua code → lualatex
  if (/\\begin\{luacode\}|\\directlua\{/.test(latexSource)) {
    return "lualatex";
  }

  // fontspec → xelatex (or lualatex, but xelatex is faster without Lua)
  if (/\\usepackage\{fontspec\}/.test(latexSource)) {
    return "xelatex";
  }

  // Default: pdflatex — fastest, widest compatibility
  return "pdflatex";
}

async function compileWithAutoEngine(latexSource: string): Promise<Buffer> {
  const engine = detectEngine(latexSource);

  const response = await fetch("https://api.formatex.io/api/v1/compile", {
    method: "POST",
    headers: {
      "X-API-Key": process.env.FORMATEX_KEY!,
      "Content-Type": "application/json",
    },
    body: JSON.stringify({ content: latexSource, engine }),
  });

  if (!response.ok) {
    const error = await response.json();
    throw new Error(`[${engine}] ${error.log ?? error.error}`);
  }

  return Buffer.from(await response.arrayBuffer());
}