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HTML to PDF

Turn your HTML into a PDF you can send.

You already made it look good on the web. Send that same HTML and get back a crisp PDF with your fonts, colours, and page breaks in place. It works from the editor, from one API call, or through your AI agent.

Start freeRead the quickstart
  • 25 free credits every month
  • No card needed
  • Failed renders cost nothing
An A4 client invoice from Northline Studio, made as a PDF
client-invoice.pdf, one A4 page, made from HTML and data

One request

Send HTML, get a PDF back.

This is the whole job. Post your HTML, then download the file from the signed link in the response. The quickstart shows how to poll and download.

POST /v1/pdf
curl --fail-with-body --silent --show-error https://thirds.ai/v1/pdf \
  -H 'Authorization: Bearer YOUR_API_KEY' \
  -H 'Content-Type: application/json' \
  -H 'Idempotency-Key: YOUR_UNIQUE_PDF_REQUEST' \
  --data '{"html":"<h1>Monthly report</h1><p>August 2026, ready to share.</p>","pdf":{"format":"A4"}}'
The finished monthly report PDF with a summary, a chart, and a tableHTML

This report was made by this API from the monthly report gallery template.

How it works

Three steps to a finished PDF.

  1. The editor's Edit source dialog with the template HTML open for editing

    Send your HTML

    Paste it in the editor, or send it from your app with one request.

  2. The editor with an A4 report page on the canvas, the layer list, and the properties panel

    We render it

    A real browser lays out your page with your fonts, colours, and images.

  3. The Renders list with PDF, WebP, JPEG, and PNG cards, each with a download link

    Download the file

    Get the PDF from a signed link, or let a webhook tell your server it is ready.

What you control

Page size, margins, and the rest.

Set the options in the request. The defaults make a clean A4 page, so you only change what you need.

Page sizes
A4, Letter, Legal, and custom sizes
Pages per PDF
Up to 100
Fonts
Web fonts, brand kit fonts, and system fonts
Credits
One credit per finished PDF
Files kept
30 days after each render
Failed renders
Free, and safe to retry

Templates with data

Save the design once, fill it with data every time.

A saved template holds the HTML. Each request sends only the data, so an invoice, a report, or a certificate comes out matching every time.

  • Fields like {{ client_name }} fill from your JSON.
  • Every version of a template stays saved, so old renders are safe.
  • Add a brand kit and the logo, colours, and fonts follow.
A campaign report PDF with charts and a summary table

Start from a real template

Copy a document template and make it yours.

See every template

Good to know

Plain limits, so nothing surprises you.

  • A PDF can hold up to 100 pages. Split a longer document into two renders.
  • Images and fonts must load from public web addresses. Private and local addresses are blocked.
  • The renderer blocks scripts that run for too long or use too much memory. The render fails and you are not charged.
  • We keep each finished file for 30 days. Download your own copy before then.

Questions

Before you start.

Does it work with CSS and web fonts?
Yes. A real Chromium browser lays out your page, so grid, flexbox, print styles, and web fonts all work the way they do on the web.
Can I use it without an account?
Every render needs an account, because each finished file costs one credit. The free plan gives you 25 credits every month with no card.
How fast is it?
Most single-page PDFs finish in a few seconds. Long documents with many images take longer. Use wait or poll the job to get the result.
I use wkhtmltopdf today. Can I move?
Yes. Most pages need no change at all. Read the guide on moving from wkhtmltopdf for the few differences.

Go deeper

Everything you need to ship PDFs.

Start now

Your first PDF is free.

Sign in, paste some HTML, and download the file. The free plan includes 25 credits every month.

Start freeSee the plans