Conan and vcpkg are the two big ones, and there are several smaller ones. Since they picked up in popularity about a decade ago, it's become increasingly unusua

Conan and vcpkg are the two big ones, and there are several smaller ones. Since they picked up in popularity about a decade ago, it's become increasingly unusual for "header only" to be a selling point for a library (though of course some naturally are if they're fully templated).