AROS (Amiga Research Operating System) is a free, open-source reimplementation of the AmigaOS API. The goal is API compatibility with AmigaOS 3.1 at source code level. AROS runs natively on x86 PCs (including 64-bit), ARM (Raspberry Pi), and as a hosted version under Linux/Windows. AROS offers: Wanderer (Workbench clone), Zune (MUI clone), Shell, TCP/IP stack, USB support, RTG graphics. Icaros Desktop and AspireOS are popular AROS distributions. AROS is actively developed and completely free.