(In approximately reverse-chronological order of release; active projects printed in bold)
| Name | CPU | Implementation language | License | Main author / Maintainer | Organization |
|---|---|---|---|---|---|
| Pistachio | Pentium or better, IA64, PowerPC, Alpha, 64-bit MIPS | C++ | BSD license | L4KA team | L4KA at Uni KA and UNSW |
| Fiasco | i486 or better, StrongARM, Linux (user-mode L4 emulation) | C++ | GPL or commercial | Michael Hohmuth and Team Fiasco | TU Dresden |
| P4 | x86, MIPS, PowerPC, ARM | C | commercial | Robert Kaiser | Sysgo AG | L4 for PowerPC | PowerPC 603e | C | Not yet available | Mike Bennett | Univ. of York |
| Hazelnut *1 | Pentium or better, StrongARM | C++ | GPL or commercial | L4KA team | L4KA at Uni KA |
| L4/MIPS *1 | MIPS R4x00 | C | GPL | Kevin Elphinstone / Gernot Heiser | UNSW |
| L4/Alpha *1 | Alpha AXP 21264 | Assembly language | GPL | Sebastian Schönberg / Daniel Potts / Simon Winwood | TU Dresden, UNSW |
| L4/x86 (aka. Lava Nucleus, aka Lemon Pip) *1 | i486 or better | Assembly language | *2 | ">Jochen Liedtke | GMD, IBM Watson, Uni KA |
Notes: