libobjfw is known to work on the following platforms, but should run on
many others as well:
+-------------------------+--------------+----------------------+
| OS | Architecture | Compiler |
+-------------------------+--------------+----------------------+
| FreeBSD >= 8.0 | x86 | |
+-------------------------+--------------+----------------------+
| Linux | x86 | gcc 4.4.1 |
| Linux | x86 | llvm/clang r83252 |
| Linux | x86_64 | gcc 4.4.1 |
+-------------------------+--------------+----------------------+
| iPhone OS >= 2.2.1 | arm | gcc 4.2 |
| Mac OS X >= 10.5 | ppc | gcc 4.0 + 4.2 |
| Mac OS X >= 10.5 | ppc64 | gcc 4.0 + 4.2 |
| Mac OS X >= 10.5 | x86 | gcc 4.0 + 4.2 |
| Mac OS X >= 10.5 | x86_64 | gcc 4.0 + 4.2 |
+-------------------------+--------------+----------------------+
| NetBSD >= 4.0 | x86 | gcc 4.1.2 prerelease |
+-------------------------+--------------+----------------------+
| OpenBSD >= 4.6 | x86_64 | gcc 4.2.4 |
+-------------------------+--------------+----------------------+
| OpenSolaris >= 2009.06 | x86 | |
| OpenSolaris >= 2009.06 | x86_64 | |
+-------------------------+--------------+----------------------+
| Windows >= XP / cygwin | x86 | |
| Windows >= XP / mingw32 | x86 | |
+-------------------------+--------------+----------------------+
Basically, it should run on any POSIX system to which gcc4 has been
ported. If not, please send a bug report.