Lucet 
A Bytecode Alliance project
Lucet is a native WebAssembly compiler and runtime. It is designed to safely execute untrusted WebAssembly programs inside your application.
Check out our announcement post on the Fastly blog.
Lucet uses, and is developed in collaboration with, the Bytecode Alliance's Cranelift code generator. It powers Fastly's Terrarium platform.
Lucet's documentation is available at https://bytecodealliance.github.io/lucet (sources).