bisq-network/bisq

Bitcoin Core is the reference implementation of the Bitcoin protocol, hosted at bitcoin/bitcoin on GitHub. Per its README, it joins the Bitcoin peer-to-peer network to independently validate blocks and transactions, ships an optional wallet and GUI, and is written in C++ under the MIT license.

CS-Notes is a GitHub repository maintained by CyC2018 that collects Chinese-language study notes across ten topic areas: algorithms, operating systems, networking, object-oriented design, databases, Java, system design, tools, coding practice, and an afterword. It links each topic to standalone markdown files instead of writing everything inline, and the README says most of the content is original work rather than material copied from elsewhere.

Java Design Patterns is an open-source GitHub project by iluwatar that documents design patterns as commented, working Java code rather than diagrams or prose. The repository is organized so readers can find a pattern by name, by tag such as Gang of Four or Performance, or by category, with a companion site and an optional paid e-book alongside it.

Syncthing is an open source, continuous file synchronization program from the syncthing/syncthing repository on GitHub, written in Go and released under the MPL-2.0 license. It keeps files matched across two or more computers over a peer-to-peer connection, and its own README ranks data safety and security against attackers ahead of ease of use among its stated goals.