List of free, open source operating systems

Updated: April 26, 2025

  1. OpenBSD
  2. Linux
  3. FreeBSD
  4. NetBSD
  5. Dragonfly BSD
  6. Qubes OS
  7. Haiku
  8. Redox
  9. ReactOS
  10. AROS
  11. FreeDOS
  12. BASIC-DOS
  13. Blog series: Writing an OS in Rust
  14. skiftOS
  15. RetrOS-32
  16. Tock
  17. Hubris
  18. Essence
  19. Subgraph OS
  20. Ares
  21. osv.io
  22. axle OS
  23. Snowdrop OS
  24. vekos
  25. Essence
  26. Barrelfish
  27. ToaruOS
  28. Mezzano
  29. House
  30. Minoca OS
  31. Kerla
  32. SOS
  33. PowerNex
  34. Interim OS
  35. KolibriOS
  36. MINIX
  37. RISC OS
  38. HelenOS
  39. GeckOS/A65 V2.0
  40. Serenity
  41. GNU Hurd
  42. Plan 9
  43. Harvey
  44. illumos
  45. AquilaOS
  46. NuttX
  47. Sculpt
  48. Biscuit
  49. Xv6