API Documentation

Compile LaTeX documents to PDF via a simple HTTP API.

Introduction

The LaTeX Compiler API lets you compile LaTeX source code into PDF documents programmatically. Send your .tex files, get back a base64-encoded PDF. Supports single-file and multi-file projects with images, bibliographies, and custom packages.

Use it to build CI/CD pipelines for academic papers, generate PDFs from templates in your app, or integrate LaTeX compilation into any workflow.

Authentication

All API requests require an API key passed in the x-api-key header. Keys are prefixed with lx_ and can be created from your account dashboard.

# Include your API key in every request
curl -H "x-api-key: lx_your_key_here" ...

Base URL

All API endpoints are relative to:

https://latex.spicychai.com

Compile LaTeX

Compile LaTeX source into a PDF document. Supports two modes: single-file (pass raw LaTeX) or multi-file (pass a file map).

Request Body

Response

Success (200):

{
  "success": true,
  "pdf": "JVBERi0xLjQK..."  // base64-encoded PDF
}

Failure (200):

{
  "success": false,
  "error": "Compilation failed",
  "log": "! Undefined control sequence..."  // last 2000 chars of pdflatex log
}

Examples

Single file (curl):

bashcurl -X POST https://latex.spicychai.com/api/v1/compile \
  -H "Content-Type: application/json" \
  -H "x-api-key: lx_your_key_here" \
  -d '{
    "latex": "\\documentclass{article}\n\\begin{document}\nHello, world!\n\\end{document}"
  }' \
  | jq -r '.pdf' | base64 -d > output.pdf

Multi-file project (curl):

bashcurl -X POST https://latex.spicychai.com/api/v1/compile \
  -H "Content-Type: application/json" \
  -H "x-api-key: lx_your_key_here" \
  -d '{
    "files": {
      "main.tex": "\\documentclass{article}\n\\input{chapters/intro}\n\\begin{document}\n\\maketitle\n\\intro\n\\end{document}",
      "chapters/intro.tex": "\\newcommand{\\intro}{\\section{Introduction}\nThis is the intro.}"
    },
    "mainFile": "main.tex"
  }'

JavaScript (Node.js):

javascriptconst response = await fetch('https://latex.spicychai.com/api/v1/compile', {
  method: 'POST',
  headers: {
    'Content-Type': 'application/json',
    'x-api-key': process.env.LATEX_API_KEY
  },
  body: JSON.stringify({
    latex: '\\documentclass{article}\n\\begin{document}\nHello!\n\\end{document}'
  })
});

const { success, pdf, error } = await response.json();

if (success) {
  // pdf is a base64 string — write to file or send to client
  fs.writeFileSync('output.pdf', Buffer.from(pdf, 'base64'));
} else {
  console.error('Compilation failed:', error);
}

Python:

pythonimport requests, base64

response = requests.post(
    "https://latex.spicychai.com/api/v1/compile",
    headers={"x-api-key": "lx_your_key_here"},
    json={"latex": r"\documentclass{article}\begin{document}Hello!\end{document}"}
)

data = response.json()
if data["success"]:
    with open("output.pdf", "wb") as f:
        f.write(base64.b64decode(data["pdf"]))
else:
    print("Error:", data["error"])

Binary Files (Images)

When using the files field, PNG images can be included as base64-encoded strings. Files ending in .png with valid base64 content are automatically decoded to binary.

json{
  "files": {
    "main.tex": "\\documentclass{article}\n\\usepackage{graphicx}\n\\begin{document}\n\\includegraphics{logo.png}\n\\end{document}",
    "logo.png": "iVBORw0KGgoAAAANSUhEUg..."
  }
}

Create API Key

Create a new API key. Requires authentication via Firebase Bearer token (i.e., you must be signed in). The full key is returned once in the response and is never stored in plain text.

Request

Headers

Response

{
  "id": "abc123",
  "key": "lx_a1b2c3d4e5f6...",   // save this — shown only once
  "name": "CI Pipeline",
  "prefix": "lx_a1b2",
  "createdAt": "2026-02-17T12:00:00.000Z"
}

List API Keys

List all API keys for the authenticated user. Key secrets are never included — only the prefix, name, and usage stats.

Response

{
  "keys": [
    {
      "id": "abc123",
      "name": "CI Pipeline",
      "prefix": "lx_a1b2",
      "createdAt": "2026-02-17T12:00:00.000Z",
      "lastUsedAt": "2026-02-17T14:30:00.000Z",
      "requestCount": 42
    }
  ]
}

Revoke API Key

Permanently revoke an API key. Any requests using this key will immediately start returning 401. This action cannot be undone.

Response

{
  "success": true
}

Error Codes

Rate Limits & Credits

API requests consume credits from your account balance. Each compiled PDF page costs 1 credit.

• 100 free credits per month (granted every 30 days)
• Additional credits available via the dashboard:
  • Starter: 500 credits / $4.99
  • Standard: 1,500 credits / $9.99
  • Pro: 5,000 credits / $24.99

If your account has insufficient credits, compilation will still succeed but credit deduction will fail and the request may be rejected. Monitor your balance via the dashboard.