A short list with awesome things that I use or find interesting. For a curated list you might want to check https://github.com/sindresorhus/awesome 😛
Free DNS
Free DNS Hosting, Dynamic DNS Hosting, Static DNS Hosting, sub-domain and domain hosting.
Qt
A must-have library for any C++ developer
Using Ghost
Ghost is a fully open source, adaptable platform for building and running a modern online publication.
KiCad
A Cross Platform and Open Source Electronics Design
ESP-IDF
ESP-IDF is the official development framework for the ESP32 chip.
reichelt.de
The store from where I like to buy my electronic components and devices. It has a fast delivery and always delivered the correct components nicely packed and in time.