Auto-Generate PDF Invoices in Your SaaS App with One API Call

Every SaaS app eventually needs to send invoices. And every time, developers reach for a PDF library — pdfkit, puppeteer, jsPDF — and spend days wiring it up. There's a better way. Here's how to auto-generate a pixel-perfect PDF invoice from a Stripe webhook in under 20 lines of code. The Problem with PDF Libraries If you've ever used pdfkit or puppeteer directly in production, you know the pain: You bundle a headless browser or a heavy library into your app You write 200+ lines of layout code for a simple invoice It breaks on every Node.js version upgrade You deal with font rendering, page breaks, and margins manually For a SaaS app, this is a distraction from your core product. The Setup: Stripe Webhook + RenderPDFs Here's the full flow: Customer pays → Stripe fires invoice.payment_succeeded Your webhook handler builds an HTML invoice template You call RenderPDFs API → get back a PDF URL You email the PDF link to your customer Let's build it. Step 1: The Invoice HTML Template Design