| Operating System | Version | Architecture | Compiler | flnews | GUI library | TLS library | Notes |
|---|---|---|---|---|---|---|---|
| AIX | 5.1 | powerpc | GCC 3.4.6 | 1.2.1 | FLTK 1.4.0 | OpenSSL 1.0.2a | RS/6000 Model 42T (PowerPC 604) |
| 5.1 | powerpc | GCC 3.4.6 | 1.0.0 | FLTK 1.3.2 | OpenSSL 1.0.2a | RS/6000 Model 42T (PowerPC 604) | |
| GNU/Linux | 5.4.112 | amd64 | GCC 10.2.0 | 1.0.0 | FLTK 1.3.5 | OpenSSL 1.1.1k | Core i5-2540M |
| 3.2.0 | powerpc | GCC 6.5.0 | 1.2.1 | FLTK 1.4.0 | OpenSSL 3.0.0 | Power Mac G5 (PowerPC 970FX) | |
| 2.2.7 | i386 | EGCS 2.91.66 | 1.2.0 | FLTK 1.3.0 | OpenSSL 1.0.0 | Pentium 1, glibc 2.0.7 | |
| HP-UX | 11.11 | hppa | GCC 4.0.1 | 1.2.1 | FLTK 1.4.0 | OpenSSL 1.0.2u | HP 9000 Model D230 (PA-7300LC) |
| 11.11 | hppa | GCC 4.0.1 | 1.2.0 | FLTK 1.3.2 | None | HP 9000 Model D230 (PA-7300LC) | |
| macOS | 12.1 | aarch64 | Clang 13.0.0 | 1.0.1 | FLTK 1.4.0 | OpenSSL 1.1.1m | FLTK with Cocoa backend |
| 11.3 | amd64 | Clang 12.0.5 | 1.0.0 | FLTK 1.4.0 | OpenSSL 1.1.1k | FLTK with Cocoa backend | |
| NetBSD | 10.0 | amd64 | GCC 10.5.0 | 1.2.1 | FLTK 1.4.0 | OpenSSL 3.1.5 | Opteron 6320 |
| 9.3 | amd64 | GCC 7.5.0 | 1.2.0 | FLTK 1.3.8 | OpenSSL 1.1.1t | Opteron 6320 | |
| 9.0 | amd64 | GCC 10.2.0 | 1.0.0 | FLTK 1.4.0 | OpenSSL 3.0.0-alpha16 | Opteron 6320 | |
| 9.0 | amd64 | GCC 7.4.0 | 1.0.0 | FLTK 1.3.6 | OpenSSL 1.1.1j | Opteron 6320 | |
| 7.1.1 | sparc | GCC 4.8.5 | 1.2.0 | FLTK 1.3.3 | OpenSSL 1.0.1u | SPARCstation 20 (sun4m, SuperSPARC) | |
| 2.0 | i386 | GCC 3.3.3 | 1.0.0 | FLTK 1.3.4 | None | Pentium 1, GNU awk | |
| OpenBSD | 7.5-current | amd64 | Clang 16.0.6 | 1.2.1 | FLTK 1.3.3 | LibreSSL 3.9.0 | Core i7-7500U |
| 7.3-current | amd64 | Clang 13.0.0 | 1.2.0 | FLTK 1.3.3 | LibreSSL 3.8.1 | Core i7-7500U | |
| 7.1-current | amd64 | Clang 13.0.0 | 1.1.0 | FLTK 1.3.3 | LibreSSL 3.5.2 | Core i7-7500U | |
| 6.9-current | amd64 | Clang 11.1.0 | 1.0.0 | FLTK 1.3.3 | LibreSSL 3.4.0 | Core i7-7500U | |
| Solaris | 7 | sparc64 | SunPro 5.5 | 1.0.1 | FLTK 1.3.3 | None | Ultra 1E (sun4u, UltraSPARC) |