A list of the best online courses and tutorials to learn geospatial development.
GEOG 585 - Open Web Mapping - Lesson 6 (Archived Version) - Penn State University
Learning Open Web Mapping from Start to Finish - Penn State University
OpenLayers 6 From Scratch With A Project - Udemy
OpenLayers Workshop - openlayers.org
OpenLayers Tutorials - openlayers.org
OpenLayers 3: Beginner's Guide - Thomas Gratier , Paul Spencer , Erik Hazzard
Openlayers 3: Beginner's Guide (Code Examples) - Thomas Gratier , Paul Spencer , Erik Hazzard
OpenLayers 3.x Cookbook - Second Edition - Peter J. Langley , Antonio Santiago Perez
Mastering OpenLayers 3 - Gábor Farkas
OpenLayers API Documentation
Open Web Mapping - Lesson 6 - PennState University
Display and analyze GIS data on the web with Leaflet - Udemy
Mapping in Leaflet JS - Udemy
Leaflet Quick Start Guide (official)
Leaflet Examples (official)
LeafletJS - Quick Guide - Tutorialspoint
Leaflet.js Essentials - Paul Crickard
Instant Interactive Map designs with Leaflet JavaScript Library How-to - Jonathan Derrough
Web Application Development for Geospatial Professionals - PennState University
Dojo Toolkit Tutorials
GIS Advanced Python Programming for GIS - PennState University
PyQGIS Developer Cookbook
Cheat sheet for PyQGIS (official) GIS Programming and Software Development - PennState University
GIS Advanced Python Programming for GIS - PennState University
QGIS Server Guide/Manual"