Google Calendar - Spend less time managing your day & more time enjoying it
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.
Tweek.so - A concise and simple weekly to do list calendar app to organize your tasks online. A lightweight weekly planner to maintain your focus and boost productivity week over week.
PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
Todoist - Todoist is a to-do list that helps you get organized, at work and in life.
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents