The following libraries are used in ezEngine:

UTF8-CPP A library that provides Unicode related functionality.
zlib: Provides algorithms for zip compression and decompression. It is used by ezCompressedStreamReaderZlib and ezCompressedStreamWriterZlib.
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).
Lua: The Lua scripting language. Can be used directly or through ezLuaWrapper for easier access to common functionality.
mikktspace: Tangent space generation code by Morten S. Mikkelsen. See https://wiki.blender.org/index.php/Dev:Shading/Tangent_Space_Normal_Maps for more information. It is used by ezGeometry.
Silk Icons: Icons from this set are used by the tools.
Microsoft DirectXTex: Used by the ezTexConv tool for block compression.
stb: Public domain licensed code by Sean Barrett. Used by ezImage to read and write some of the supported formats like PNG and JPEG.
dear imgui: Library for easy debug GUIs. MIT license. Also uses several files from stb
Assimp: Open Asset Import Library, a portable Open Source library to import various well-known 3D model formats in a uniform manner.
Recast A library to generate navigation meshes from arbitrary 3D geometry.
xxHash A very fast hash algorithm.
zstd A very fast lossless compression library. It is used by ezCompressedStreamReaderZstd and ezCompressedStreamWriterZstd.