Turn HTML and CSS into a PDF: invoices, receipts, reports, tickets. Rendered by Chromium, so modern CSS (flexbox, grid, web fonts) works. Here is the whole call in Python, with the output it produced when we ran it.
Before you start
An API key. Create a free account; it comes with free tokens every month. Put the key in an environment variable so it stays out of your code: export BLOODWEB_KEY=your_key
Python 3 with the requests library: pip install requests
The input file in the same folder: invoice.html. Use your own; that is the name the code expects.
The code
Save it as html-to-pdf.py and run python3 html-to-pdf.py.
import os
import requests
resp = requests.post(
"https://bloodweb.net/api/v1/html-to-pdf",
headers={"Authorization": f"Bearer {os.environ['BLOODWEB_KEY']}"},
data={"format": "A4", "html": open("invoice.html", encoding="utf-8").read()},
timeout=120,
)
if not resp.ok:
raise SystemExit(f"{resp.status_code}: {resp.json()['error']['message']}")
with open("invoice.pdf", "wb") as f:
f.write(resp.content)
What you get
Tested 19 October 2026: this exact code ran against our test copy of the API, which runs the same service code as bloodweb.net, and produced this.
It writes invoice.pdf: a PDF, 1 page, 24 KB.
Page 1 of the result.
Change the call
Every option the HTML to PDF takes. Add or change them the same way as the ones in the code.
html: The HTML. It must be self-contained: inline <style>, and images and fonts as data: URIs. Remote files and scripts are not loaded.
format: Paper size. When format, landscape and margin are all left out, the page's own CSS @page rule decides. One of: A3, A4, A5, Letter, Legal, Tabloid.
landscape: Landscape orientation.
margin: Page margin in millimetres.
background: Print background colours and images.
page_numbers: Print "Page 1 of 3" at the bottom centre of every page.
If it fails
A failed call is not charged. The answer is JSON with an error object; the code above prints its message. The usual ones:
401missing_key or invalid_key: BLOODWEB_KEY is not set in the shell that runs the code, or the key was revoked.
400bad_param: a value is wrong or missing. The message names the parameter.
402insufficient_tokens: the balance does not cover the call. Top up in the dashboard.
429rate_limited: too many calls at once. Wait the seconds in the Retry-After header and send it again.
