List of free, open source operating systems

Updated: December 20, 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. hk
  24. Snowdrop OS
  25. Astral
  26. vekos
  27. Essence
  28. Barrelfish
  29. ToaruOS
  30. MyraOS
  31. Mezzano
  32. House
  33. Minoca OS
  34. Kerla
  35. SOS
  36. PowerNex
  37. Interim OS
  38. KolibriOS
  39. MINIX
  40. RISC OS
  41. HelenOS
  42. GeckOS/A65 V2.0
  43. Serenity
  44. GNU Hurd
  45. Plan 9
  46. Harvey
  47. illumos
  48. AquilaOS
  49. NuttX
  50. Sculpt
  51. Biscuit
  52. Xv6