1.torvalds / linuxLinux kernel source treeCOther license254K total67K forks+24,069 starsfrom 230,224 · score 10.09
2.mit-pdos / xv6-riscvXv6 for RISC-VCOther license11K total4.6K forks+1,269 starsfrom 9,474 · score 7.15
3.reactos / reactosA free Windows-compatible Operating Systemoperating-systemckernelososdevx86+7 moreCGPL-2.018K total2.3K forks+1,091 starsfrom 17,336 · score 7.00