The majority of the Synchronet executable files and libraries for Windows are (as of v3.16b development, started March, 2014) built with Microsoft Visual Studio Express 2013 for Windows Desktop (free).
Certain GUI components (e.g. Synchronet Control Panel,
sbbsctrl.exe) are currently built with Borland C++Builder 6, with efforts under way to transition to Embarcadero Technologies C++Builder (not free).
The Synchronet Windows 95 FOSSIL driver (
sbbsexec.vxd) cannot currently be rebuilt with modern Windows tools and SDKs.
The 16-bit portion of the Synchronet FOSSIL driver (
dosxtrn.exe) can be rebuilt using Microsoft Visual C++ v1.52 (16-bit).
GNU C/C++ (gcc) is officially supported on Unix/Linux platforms, while other compilers (e.g Intel C Compiler, Clang) may be used by experienced programmers.