It's a runtime for WASI blobs (basically a WASM based standard for crossplatform command line tools), for instance:

    emcc hello.c -o hello.wasm
    wasmer hello.wasm
    Hello World!

This uses Emscripten as C compiler, but alternatively you can use the wasi-sdk toolchain instead of Emscripten to build WASI blobs:

- https://github.com/WebAssembly/wasi-sdk

...or Zig as C compiler:

    zig cc -target wasm32-wasi hello.c -o hello.wasm
    wasmer hello.wasm
    Hello World!

...or of course Zig as Zig compiler :)

    zig -target wasm32-wasi hello.zig
    wasmer hello.wasm
    Hello World!

(not sure if the Rust toolchain comes with builtin WASI support, but probably yes).

...or instead of wasmer use another WASI runtime:

- https://github.com/wasmerio/awesome-wasi?tab=readme-ov-file#...

...this is probably the best part of WASM and WASI, there's no 'vendor lock-in'.