FEX-Emu
FEX-Emu is a usermode x86 and x86-64 emulator, supporting arm64 and x86-64 hosts. It is similar to qemu and box86, though it follows a different approach, using an SSA based IR.
My contributions have focused around performance and compatibility, as I love optimization problems and solving bugs.
After a fall-out with the team, some related, private/forked work can be found at the hex-emu gitlab.