jart/cosmopolitan

Cosmopolitan Libc is a C library that lets you compile a C or C++ program once and have the resulting binary run natively on Linux, macOS, Windows, FreeBSD, OpenBSD, NetBSD, and even BIOS without needing a virtual machine or interpreter. It achieves this by configuring standard compilers (GCC and Clang) to output a special file format called an Actually Portable Executable (APE), a POSIX-approved polyglot format that each operating system can understand and run directly. The key value proposition is eliminating the "build once per target platform" problem. Normally, if you want a C program to run on both Linux and Windows, you need separate build toolchains and outputs for each. Cosmopolitan produces a single binary that works everywhere. The project ships its own compiler wrapper called cosmocc, which developers use in place of a standard C compiler. Existing open-source projects that use the autotools build system can often be compiled with Cosmopolitan with minimal changes. Built-in debugging aids include --strace (logs system calls) and --ftrace (logs function call traces) flags that any Cosmopolitan program can accept at runtime. The project supports x86-64 hardware and is crowdfunded through GitHub Sponsors and Patreon.