Even neglecting Godbolt, Cppreference, and Coliru.

Godbolt is Compiler Explorer, mainly to look at assembly output, but provides editing, benchmarking, and profiling of many languages and compiler versions. I think Godbolt delegates running code to some other site, don't recall who.

Cppreference.com is mainly a C++ and C language and library standards reference library, but provides sample programs and means to run them on various compiler versions.

That uses Coliru, which also provides edit, build, and run.