Fattmerchant - Subscription-based credit card payment processing platform
pdflayer - Free, powerful HTML to PDF API supporting both URL and raw HTML conversion. Unlimited document size, lightning-fast and compatible PHP, Python, Ruby, etc.
PaymentCloud - PaymentCloud is a feature-rich Credit Card Processing solution that is created to help retailer and e-Commerce businesses to streamline all their payment operations.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
Helcim - Helcim is a feature-rich online solution that facilitates payment procedures by enabling a range of industries as well as businesses to accommodate several payment options.
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents