PDFShift - Convert any HTML documents to high-fidelity PDF using a single POST request
Minimal Calendar For 2021 - Dark & light, printable calendars for minimal offices
Tcpdf - TCPDF: Open Source PHP Class for generating PDF documents
Calendar Generator - 12 weeks on one physical page
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.
Photo Calendar Creator - Photo Calendar Creator is a convenient program for making calendars for any year or month.