Five free C C++ Fortran compiler families

Five modern, currently-supported compiler families are free-to-use for C, C++ and Fortran.

GCC has broad support of modern standards on a very wide range of computing platforms. GCC’s downside in some cases can be slower runtime performance than compilers having less broad language and platform support.

Compiler language standard
gcc C17
g++ C++20
gfortran Fortran 2018

Intel oneAPI compilers are free to use for any user. The Intel performance libraries like MKL, IPP, and TBB are available at no cost.

Compiler language standard
icx C17
icpx C++20
ifort / ifx Fortran 2018

LLVM Clang and Flang have significant industry support, including from Nvidia, and are known for high performance.

Compiler language standard
clang C17
clang++ C++20
flang Fortran 2018 (coming ~2022)

Nvidia HPC SDK is free to use. A key feature of the HPC SDK compilers is intrinsic support for CUDA Fortran.

Compiler language standard
nvc C11
nvc++ C++17
nvfortran Fortran 2003

IBM XL compilers are currently for POWER CPUs only e.g. ppc64le. IBM XL compilers do not work with a typical x86-based computer. If you have a $3000 Raptor IBM POWER9 desktop, then IBM XL may be for you. IBM is working on LLVM upgrade for its compilers.

The IBM XL compilers are high-performance compilers that have a free community edition. IBM XL Fortran has wide support for Fortran 2008. However, the XL compilers have bugs in newer language support, so be sure to check with another compiler on the IBM system like GCC if a bug is suspected.

Compiler language standard
xlc C11
xlc++ C++14
xlf Fortran 2008

IBM Fortran 2008 reference