QEMU

QEMU (Quick Emulator) is a free, open-source machine emulator and virtualizer that performs hardware virtualization using dynamic binary translation (DBT) to achieve near-native performance. Originally created by Fabrice Bellard in 2003 and now maintained by the QEMU community, it has become the most widely used open-source virtualization technology with over 10,800 stars as of 2026. QEMU operates in two modes: full-system emulation (emulating an entire computer system including CPU, memory, disk, network, graphics, and peripheral devices, enabling running unmodified guest operating systems for any architecture on any host) and user-mode emulation (running individual Linux programs compiled for one CPU architecture on another CPU, useful for cross-compilation testing and running ARM/x86 binaries on foreign architectures). QEMU supports emulating over 20 CPU architectures including x86, x86-64, ARM (Cortex-A series, AArch64), RISC-V (RV32, RV64), MIPS, PowerPC, SPARC, Alpha, S390x, m68k, Microblaze, Nios2, Or1k, and Xtensa. When used with KVM (Linux Kernel Virtual Machine) or Apple Hypervisor.framework on macOS, QEMU achieves native-speed virtualization by executing guest code directly on the host CPU with hardware virtualization extensions (Intel VT-x, AMD-V, ARM EL2). Key features include: live migration between hosts, snapshot and save/restore, incremental backup with dirty bitmap, VirtIO devices for paravirtualized I/O performance, USB device passthrough, GPU passthrough (VFIO), network bridging and NAT, disk image formats (QCOW2 with copy-on-write, thin provisioning, encryption, and compression, raw, VMDK, VDI, VHD), SPICE and VNC for remote display, TPM emulation (both TPM 1.2 and TPM 2.0), secure boot support, and QMP (QEMU Machine Protocol) JSON API for programmatic control. QEMU powers major platforms including Android Emulator, Docker Desktop, KVM-based cloud instances at AWS, Google Cloud, and Azure.