Compiler Explorer is an interactive compiler. The left-hand pane shows editable C, C++, Rust, Go, D, Haskell, Swift and Pascal code. The right, the assembly output of having compiled the code with a given compiler and settings. Multiple compilers are supported, and the UI layout is configurable (thanks to GoldenLayout). There is also an ispc compiler ? for a C variant with extensions for SPMD. You can support this project on Patreon.