Developer API

Connect your apps and agents to Mathfold. Keys belong to your account and use your plan's API quota.

Quick start

API reference

Mathfold converts Markdown into Word (.docx), PDF or print-ready HTML over HTTP. The REST API and the MCP server use the same engine as the web app, so a document looks the same however it was made. The machine-readable description is at /openapi.json.

Authentication

Create a key on this page after signing in with Google. Send it with every request:

Authorization: Bearer mf_YOUR_KEY

The X-API-Key: mf_YOUR_KEY header works too. Keys count against your plan: 100 calls a month on Free (watermarked) and 1,000 a month on Pro. Each key is limited to 60 requests a minute.

POST /v1/convert

Send raw Markdown as the body and choose options with query parameters:

curl -X POST "https://mathfold.com/v1/convert?format=docx&theme=standard" \
  -H "Authorization: Bearer mf_YOUR_KEY" \
  -H "Content-Type: text/markdown" \
  --data-binary @answer.md -o answer.docx

Or send JSON, which also lets you attach images that the Markdown references by file name:

{
  "markdown": "# Report\n\n![chart](chart.png)\n\n$$E = mc^2$$",
  "format": "pdf",
  "options": { "theme": "academic", "pageSize": "Letter", "toc": true },
  "files": { "chart.png": "<base64>" }
}

Option	Values	Default
`format`	`docx`, `pdf`, `html`	`docx`
`theme`	`standard`, `academic`, `modern`, `compact` (all but standard need Pro)	`standard`
`pageSize`	`A4`, `Letter`, `A5`, `A3`, `Legal`	`A4`
`orientation`	`portrait`, `landscape`	`portrait`
`autoLandscape`	`true`, `false`: give wide tables and diagrams landscape pages	`true`
`toc`	`true`, `false`: start with a table of contents	`false`
`title`	Text used when the document has no title	none
`mathMode`	`auto`, `latex`, `asciimath`	`auto`

The response is the file itself, with Content-Disposition, X-Watermarked (1 or 0) and X-Calls-Remaining headers. Send Accept: application/json to get { filename, mime, base64, watermarked, warnings, remaining } instead.

Errors

Errors are JSON: { "error": "code", "message": "..." }.

Status	Code	Meaning
400	`empty_markdown`, `bad_format`, `bad_json`	The request is incomplete or malformed
401	`invalid_api_key`	Missing, wrong or revoked key
402	`quota_exceeded`	Monthly API calls used up
402	`pro_theme`	The theme needs Pro
413	`payload_too_large`	Body over 8 MB
429	`rate_limited`	Over 60 requests a minute; see `retryAfterSeconds`

MCP server

https://mathfold.com/mcp is a remote MCP server (Streamable HTTP) with one tool, convert_markdown. It takes markdown plus optional format, theme, pageSize, toc and title, and returns a download link that stays valid for 30 minutes. Add it to Claude Code:

claude mcp add --transport http mathfold https://mathfold.com/mcp \
  --header "Authorization: Bearer mf_YOUR_KEY"

Or to any client that reads an mcp.json:

{ "mcpServers": { "mathfold": {
    "url": "https://mathfold.com/mcp",
    "headers": { "Authorization": "Bearer mf_YOUR_KEY" } } } }