Generating PDFs from HTML involves multiple approaches with varying levels of fidelity, performance, and complexity. Choosing the right method depends on your content type and quality requirements.
Headless Browser Rendering
Headless browsers (Puppeteer, Playwright) render HTML exactly as a real browser would, then save as PDF. This provides pixel-perfect output with full CSS, JavaScript, web fonts, and SVG support. Advantages: highest fidelity, handles complex layouts (flexbox, grid), renders JavaScript-generated content. Disadvantages: slower (1-3 seconds per page), higher resource usage (CPU, memory), requires browser binary. Best for: complex web pages, charts/graphs, modern CSS.
PDF Libraries (Direct Generation)
Libraries like PDFKit, jsPDF, or ReportLab generate PDFs programmatically without rendering HTML. You define elements via code: pdf.text("Hello"), pdf.rect(). Advantages: very fast (<100ms), lightweight, precise control over layout. Disadvantages: no HTML/CSS support, must build layouts programmatically, complex designs require significant code. Best for: simple documents, programmatic reports, templates with consistent structure.
Hybrid: HTML to PDF Libraries
Tools like wkhtmltopdf or Prince parse HTML/CSS and convert to PDF without full browser rendering. They support common CSS but not cutting-edge features. Advantages: faster than headless browsers, better than manual libraries, smaller resource footprint. Disadvantages: CSS support is incomplete (old standards), no JavaScript execution, may produce different output than browsers. Best for: simple HTML documents, legacy projects.