The following libraries are used in ezEngine:

zlib: Provides algorithms for zip compression and decompression. It is used by ezCompressedStreamReader and ezCompressedStreamWriter.
enet: An efficient and easy to use networking library, built on top of the UDP protocoll. It is used by ezTelemetry.
SFML: This library provides a simple and portable interface for window creation, input handling and more. Used by ezWindow and ezStandardInputDevice on non-Windows platforms (Mac, Linux).
GPA: When EZ_USE_PROFILING_GPA is enabled, ezEngine allows to use the Intel GPA tool for performance profiling.
Lua: The Lua scripting language. Can be used directly or through ezLuaWrapper for easier access to common functionality.
Silk Icons: Icons from this set are used by some of our tools.