MAME is a multi-purpose emulation framework
BizHawk is a multi-system emulator written in C#
Third-party TI-84 Plus CE / TI-83 Premium CE emulator
DOSBox Staging is a modern continuation of DOSBox
HLE 3DS emulator
Virtualization software for x86_64 hardware
Xbox 360 Emulator Research Project
Unicorn CPU emulator framework (ARM, AArch64, M68K, Mips, Sparc
Proxy for Lambda’s Runtime and Extensions APIs
Emulate AWS λ and API Gateway locally
Qiling Advanced Binary Emulation Framework
Play! - PlayStation2 Emulator
Gameboy emulator in Java 8
Run Windows applications on Linux, BSD, Solaris, and Mac OS X
GameCube and Wii emulator for PC (Windows, Mac, & Linux)
Z80 shared library including some nice test-projects
A portable library and tools for archiving images of Atari 8-bit tapes
Python front end for MAME that can run in Linux, Windows, and MacOS