Reta Vortaro: a community-based online dictionary Esperanto <-> any other language.
Claude Piron: articles and books linked to Esperanto and psychology.
Programming
Codewars: gives programming exercises to challenge you.
CodeAbbey: more straightforward than Codewars: problem, input, and give the right output.
Project Euler: similar to CodeAbbey, but more oriented to mathematics.
Studies
Cheatography: offers cheatsheets for many subjects.
Utilities
AlternativeTo: gives alternatives and news about softwares.
cobalt.tools: download any video/audio from any mainstream website just with a link!
privacy.sexy: gives you scripts to clean up your computer (e.g remove Edge and OneDrive), and also scripts to revert those changes if needed.
pairdrop.net: a tool to send files between your devices locally.
DISCLAIMER: These are blogs I like, but that doesn’t necessarily mean I’ll agree with everything written in them. That said I think it’s important to regularly challenge one’s critical mind.
Dig Deeper: gives an alternative point of view about software, privacy and society. Redpilled me about Mozilla;
Stop using Discord: explains what is wrong with Discord, what they hide and what they do behind your back
Less Retarded Wiki: records worldview, explanations and tutorials from an excentric weird guy. Funnier and more interesting to read than Wikipedia. Redpilled me about privacy.