Capture by Techulus - The ultimate toolkit for converting HTML to image & PDF. Pay only for what you need.No Subscription.
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.
Screenshot Machine - Screenshot machine is an online website capturing service. Creates a screenshot or thumbnail of any online web page in couple of seconds for free.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
Urlbox.io - Screenshot full page websites in retina resolution with Urlbox.io screenshot as a service API. Urlbox is the best provider of automated website screenshots offering many unique options and features.
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents