To follow on with this, I've used https://pdfcrowd.com/ too. - Source: Reddit / about 2 months ago
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
Api2Pdf - PDF Generation API, powered by AWS Lambda. HTML to PDF | URL to PDF | Office Doc to PDF | Merge PDFs . Supports wkhtmltopdf, Headless Chrome, and LibreOffice. No rate limits and no file size limits.
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents
DocRaptor - Forget tedious coding or server management: Our simple API that makes it easy to convert HTML to PDF, XLS and Excel files.
HTML2PDF - HTML2PDF is a HTML to PDF converter that allows the conversion of valid HTML 4.
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.