Arcane Algorithm Archive - A collaborative online project and website seeking to provide a guide to implementing all important algorithms. The guide includes examples which are written in multiple programming languages: https://www.algorithm-archive.org/
Geo-Python - Introduction to the basic concepts of programming and scientific data analysis using Python from the Department of Geosciences and Geography at the University of Helsinki: https://geo-python-site.readthedocs.io/
Automating GIS-Processes - A course from the the Department of Geosciences and Geography at the University of Helsinki which introduces geographic data analysis in Python: https://autogis-site.readthedocs.io/
EarthLab - Python, R tutorials and Google Earth Engine tutorials for working with geospatial, social, biological, and earth systems data: https://www.earthdatascience.org/
Geographic Data Sicence with Python - Online book by Sergio J. Rey, Dani Arribas-Bel and Levi J. Wolf providing tools, methods and theory for geographic data science with Python: https://geographicdata.science/
Bellingcat - Online resource providing how-to guides for using open data and open-source tools to perform tasks like geolocating videos, automating photo and video retrieval, verifying dates of satellite imagery, reverse image search, archiving open source materials and scraping web data: https://www.bellingcat.com/resources/
OSINT Framework - Directory of free tools and resources for use in OSINT investigations: https://osintframework.com/