Wasmer Runtime

The Wasmer Runtime is the engine that allows running WebAssembly modules and Wasmer packages anywhere.

Wasmer can be used as a library from any programming language, or as a standalone runtime via the Wasmer CLI.


  • Secure by default. No file, network, or environment access, unless explicitly enabled.
  • Fast. Run WebAssembly at near-native speeds.
  • Pluggable. Embeddable in multiple programming languages
  • Compliant with latest WebAssembly Proposals (SIMD, Reference Types, Threads, ...)


The Wasmer Runtime supports multiple backends, depending on your needs:

Native backends:

  • Singlepass: A single-pass compiler for fast compilation times and low memory usage.
  • Cranelift: A fast compiler backend with a focus on compile times, and runtime performance.
  • LLVM: A compiler backend that uses LLVM for optimization and code generation.

Integration backends:

  • Browser: it allows running Wasmer fully in the browser (via wasm-bindgen).
  • JavascriptCore: it allows running Wasmer using the WebAssembly engine inside JavascriptCore
  • V8 (coming soon): it allows running Wasmer using the WebAssembly engine inside V8