Free HTML to PDF API: convert HTML or a URL with one request

The same engine behind the converter is available as a simple HTTP API. There is no key or account: send HTML or a URL, receive a PDF. It’s rate limited and designed for light, occasional use such as scripts, prototypes and small internal tools.

Endpoints

A successful response is the PDF itself, with Content-Type: application/pdf.

curl

curl -X POST https://htmltopdf.online/api/convert/html \
  -H "Content-Type: application/json" \
  -d '{"html":"<h1>Hello</h1><p>From the API.</p>"}' \
  -o hello.pdf

curl -X POST https://htmltopdf.online/api/convert/url \
  -H "Content-Type: application/json" \
  -d '{"url":"https://example.com","settings":{"landscape":true}}' \
  -o page.pdf

curl -X POST https://htmltopdf.online/api/convert/file \
  -F "[email protected];type=text/html" \
  -F 'settings={"paper":"Letter","marginMm":15}' \
  -o invoice.pdf

JavaScript (Node 18+)

import { writeFile } from "node:fs/promises";

const response = await fetch("https://htmltopdf.online/api/convert/html", {
  method: "POST",
  headers: { "Content-Type": "application/json" },
  body: JSON.stringify({ html: "<h1>Report</h1>", settings: { paper: "A4" } }),
});
if (!response.ok) throw new Error((await response.json()).error.message);
await writeFile("report.pdf", Buffer.from(await response.arrayBuffer()));

Python

import requests

response = requests.post(
    "https://htmltopdf.online/api/convert/html",
    json={"html": "<h1>Report</h1>", "settings": {"paper": "A4", "marginMm": 12}},
    timeout=60,
)
response.raise_for_status()
open("report.pdf", "wb").write(response.content)

Settings

Missing fields use the defaults. Unknown fields are rejected, so typos surface as errors instead of being ignored.

Limits

• HTML up to 2 MiB (UTF-8); the whole request up to 3 MiB.
• PDFs up to 100 pages and 20 MiB. Larger documents are rejected, never truncated.
• 45 seconds per request.
• 10 conversions per minute per client, and a small number at the same time across the service. Busy or rate-limited requests receive 429 with a Retry-After header.
• URLs must be public http on port 80 or https on port 443.

Errors

Errors return JSON such as { "error": { "code": "URL_NOT_ALLOWED", "message": "…" } }.

Good to know

• Requests from other websites’ browser code are refused; call the API from a server or script.
• Documents aren’t saved to persistent storage. Don’t send passwords, signed URLs or sensitive private documents.
• The API is free and has no uptime guarantee. For high-volume or business-critical workloads, run your own converter.