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Guide

Invoices as PDFs, from the HTML you already have

Skip the PDF library. You already have an invoice that looks right in a browser - print that.

Most invoice PDFs are built twice: once as HTML for the web view, and again in a PDF library that lays out boxes by coordinate. The second one is where the effort goes and where the bugs live, because it has no layout engine - you are hand-placing text next to a total that moved.

Chromium already has a layout engine and a print stylesheet. Give it the HTML you have.

The request

curl -X POST https://api.ironfang.uk/renderwolf/v1/pdf \
  -H "Authorization: Bearer if_live_..." \
  -H "Content-Type: application/json" \
  -d '{
    "html": "<h1>Invoice INV-1042</h1>...",
    "print_background": true,
    "footer_html": "<div style=\"font-size:9px;width:100%;text-align:center;color:#666\">Page <span class=\"pageNumber\"></span> of <span class=\"totalPages\"></span></div>"
  }' \
  --output invoice-1042.pdf

The two settings that catch everyone

print_background: true keeps the colours. Browsers drop backgrounds when printing by default, which is sensible for a news article and wrong for an invoice with a coloured header - without it the PDF comes out looking broken rather than plain.

Inside those templates, Chrome's print classes work: pageNumber, totalPages, date, title, url. That is how you get real page numbers rather than a guess.

What it costs

A PDF is two credits rather than one, because it costs about twice as much to produce - the page is laid out, then paginated. Identical requests are served from cache and cost nothing, so re-fetching the same invoice is free.

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