PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
BookmarkSheet - Your bookmarks in Google Sheets
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents
Bookmark OS - Bookmark OS is like Mac or Windows optimized for bookmarks.
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.
Bookmark It - Create awesome notes on YouTube videos