Generating PDFs from HTML: Why It Is Harder Than You Think

The first time a client asked me to add a "Download as PDF" button to a web app, I thought it would take an afternoon. It took a week. The HTML looked perfect in the browser. The PDF output had broken layouts, missing fonts, cut-off tables, and pages that split paragraphs in the middle of sentences. Converting HTML to PDF is one of those problems that seems solved until you actually try to do it well. Why browsers and PDFs are different A browser renders HTML into a continuous, scrollable viewport. A PDF is a fixed-size, paginated document. This fundamental difference creates every problem in HTML-to-PDF conversion: Page breaks. A browser never needs to split content across pages. A PDF does. Where do you break a 3,000-pixel-tall page into letter-sized sheets? The naive approach breaks wherever the page boundary falls, even if that is in the middle of a table row, an image, or a heading that should stay with its following paragraph. Fonts. Browsers have access to system fonts and web f