Top 3 C++ public-domain Projects

G3log

0 881 7.2 C++

G3log is an asynchronous, "crash safe", logger that is easy to use with default logging sinks or you can add your own. G3log is made with plain C++14 (C++11 support up to release 1.3.2) with no external libraries (except gtest used for unit tests). G3log is made to be cross-platform, currently running on OSX, Windows and several Linux distros. See Readme below for details of usage.
nanoprintf

5 573 5.5 C++

The smallest public printf implementation for its feature set.

Project mention: nanoprintf VS callback_printf - a user suggested alternative | libhunt.com/r/nanoprintf | 2023-08-16

WorkOS

workos.com sponsored

The modern identity platform for B2B SaaS. The APIs are flexible and easy-to-use, supporting authentication, user identity, and complex enterprise features like SSO and SCIM provisioning.
gdextension

3 164 6.4 C++

GDExtension template that automatically builds into a self-contained addon for the Godot Asset Library. Updated to Godot 4.2.1. (by nathanfranke)

Project mention: How to register a native GDExtension class as Autoload? | /r/godot | 2023-11-03

The native code needs to run computations in _physics_process, therefore a regular singleton as shown here won't work.

NOTE: The open source projects on this list are ordered by number of github stars. The number of mentions indicates repo mentiontions in the last 12 Months or since we started tracking (Dec 2020).