Rtools45 for Windows - The Comprehensive R Archive Network Rtools is a toolchain bundle used for building R packages from source (those that need compilation of C C++ or Fortran code) and for building R itself Rtools45 is currently used for R 4 5 and R-devel, the development version of R, to become R 4 6 0
Howto: Building R 4. 5 and packages on Windows Rtools45 (for Intel) is best tested on Windows 10 and Windows Server 2022 It is sometimes tested on Windows 11 and expected to work there well because of Windows backward compatibility Rtools45 will not work on Windows 8 or earlier, because Msys2 no longer supports those systems