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PDF Generation API: Multi-Page Templates, Per-Page Credits

Published October 15, 2026 by Balaji

Uncategorized

A PDF generation API usually means one of two things: converting HTML, Markdown, or a URL to PDF, or filling a designed template and exporting it. jsontoimg is the second kind. Set format to pdf on the same render call you use for images, and a multi-page template becomes a multi-page PDF.

The request

curl -X POST "$JSONTOIMG_BASE_URL/api/v1/render?wait=60" \
  -H "Authorization: Bearer $JSONTOIMG_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{"template":"<design-id>","format":"pdf","layers":{"full_name":{"text":"Ada Lovelace"}}}'

Layer overrides work exactly as they do for images, and so do wait, batch, and webhooks. A misspelled layer name returns 422 Unprocessable Content instead of a PDF with placeholder text.

What a PDF costs

One credit per page.

Output Credits
1-page certificate 1
5-page proposal 5
12-page report 12
One PNG of the same design 1

Failed jobs are free, and a quota overrun returns 402 Payment Required. At the prepaid rate of $0.02 per image, a 12-page report costs $0.24. Design to the page count you need: a template with a spare page costs a credit on every render.

Rules to know

  • transparent is not valid with PDF. It works with PNG, WebP, and AVIF only.
  • wait blocks for at most 60 seconds. Longer jobs return a job id; use a webhook or poll.
  • A batch accepts up to 50 jobs, and each job sets its own format.
  • Layout comes from the editor. Content that must reflow, such as a table that grows to a second page by itself, belongs in a template where you chose the page count.

What it does not do

jsontoimg does not turn arbitrary HTML, Markdown, or a live URL into a PDF. Tools such as APITemplate.io are built around HTML-to-PDF. If your source is a web page, use a tool that renders web pages. If your source is a design with named fields, this is the shorter path.

Pairing PDF with PNG

Many certificate and ticket flows render both: a PNG for the email body and a PDF for printing, from the same template and payload. That is two credits per recipient. The pipeline is in the Certificate Generator API guide, and the format reference is in the PDF docs. The PDF format overview covers what the file type guarantees.

FAQ

How does jsontoimg generate PDFs?

Send POST /api/v1/render with format set to pdf. A multi-page template becomes a multi-page PDF, and layer overrides work as they do for images.

How are PDFs billed?

One credit per page. A 12-page report uses 12 credits, a failed job uses none, and prepaid packs work out to $0.02 per image.

Can I convert HTML or a URL to PDF with jsontoimg?

No. jsontoimg renders designs from its editor with named layers. For arbitrary HTML, Markdown, or URL conversion, use a tool built for that.

Can I make a transparent PDF?

No. The transparent option is not valid with PDF and works only with PNG, WebP, and AVIF.

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