Corrade is a multiplatform utility library written in C++11/C++14.
It's used as a base for the Magnum graphics engine, among other things.

Features:
* Low-level utilities to bridge platform differences when accessing OS
  functionality, filesystem, console and environment
* Lightweight container implementations, complementing STL features with focus
  on compilation speed, ease of use and performance
* Test framework emphasizing flexibility, extensibility, minimal use of macros
  and clarity of diagnostic output
* Plugin management library with static and dynamic plugins, dependency handling
  and hot code reload
* Signal/slot connection library with full type safety

WWW: https://magnum.graphics/corrade/