Generating invoices manually is a time sink. Whether you are running a SaaS, freelancing, or managing an e-commerce platform, automating invoice generation saves hours every month and eliminates human error. The best approach? Convert **HTML templates to PDF** using an API. In this guide, you will learn how to **automate invoice generation** by designing invoices in HTML and CSS, then converting them to pixel-perfect PDFs programmatically. ## Why HTML to PDF for Invoices? There are many ways to generate PDFs — libraries like ReportLab (Python), jsPDF (JavaScript), or wkhtmltopdf. But HTML-to-PDF has clear advantages: - **Design with familiar tools** — Use HTML and CSS, not complex PDF coordinate systems - **Pixel-perfect rendering** — The PDF looks exactly like the HTML - **Easy to maintain** — Designers can modify templates without touching code - **Dynamic content** — Use template engines to inject data - **Consistent output** — Same rendering engine every time ## Building an Invoice Template Let us start with a professional invoice HTML template: ```html
Acme Corp

INVOICE

#INV-2026-0042

Bill To

John Smith
Smith Enterprises
123 Business Ave
New York, NY 10001

Invoice Details

Date: February 12, 2026
Due Date: March 14, 2026
Payment Terms: Net 30

Description Qty Rate Amount
Web Development Services 40 hrs $150.00 $6,000.00
UI/UX Design 20 hrs $125.00 $2,500.00
Server Infrastructure (Monthly) 1 $299.00 $299.00
Subtotal $8,799.00
Tax (10%) $879.90
Total $9,678.90

Thank you for your business! Payment is due within 30 days.

Questions? Email [email protected]

``` ## Converting HTML to PDF with the API Now let us convert this template to a PDF using the ToolCenter: ### cURL Example ```bash curl -X POST "https://api.toolcenter.dev/v1/pdf" \ -H "Content-Type: application/json" \ -H "Authorization: Bearer YOUR_API_KEY" \ -d {