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cargo wasi

A Bytecode Alliance project

A lightweight Cargo subcommand to build code for the wasm32-wasi target.

Crates.io version Download docs.rs docs

Guide | Contributing


To install this Cargo subcommand, first you'll want to install Rust and then you'll execute:

$ cargo install cargo-wasi

After that you can verify it works via:

$ cargo wasi --version

Read more about installation in the guide!


The cargo wasi subcommand is a thin wrapper around cargo subcommands, providing optimized defaults for the wasm32-wasi target. Using cargo wasi looks very similar to using cargo:

  • cargo wasi build — build your code in debug mode for the wasi target.

  • cargo wasi build --release — build the optimized version of your *.wasm.

  • cargo wasi run — execute a binary.

  • cargo wasi test — run your tests in wasm32-wasi.

  • cargo wasi bench — run your benchmarks in wasm32-wasi.

In general, if you'd otherwise execute cargo foo --flag you can likely execute cargo wasi foo --flag and everything will "just work" for the wasm32-wasi target.

To give it a spin yourself, try out the hello-world versions of programs!

$ cargo new wasi-hello-world
     Created binary (application) `wasi-hello-world` package
$ cd wasi-hello-world
$ cargo wasi run
   Compiling wasi-hello-world v0.1.0 (/code/wasi-hello-world)
    Finished dev [unoptimized + debuginfo] target(s) in 0.15s
     Running `cargo-wasi target/wasm32-wasi/debug/wasi-hello-world.wasm`
     Running `target/wasm32-wasi/debug/wasi-hello-world.wasm`
Hello, world!

Or a library with some tests:

$ cargo new wasi-hello-world --lib
     Created library `wasi-hello-world` package
$ cd wasi-hello-world
$ cargo wasi test
   Compiling wasi-hello-world v0.1.0 (/code/wasi-hello-world)
    Finished dev [unoptimized + debuginfo] target(s) in 0.19s
     Running target/wasm32-wasi/debug/deps/wasi_hello_world-9aa88657c21196a1.wasm
     Running `/code/wasi-hello-world/target/wasm32-wasi/debug/deps/wasi_hello_world-9aa88657c21196a1.wasm`

running 1 test
test tests::it_works ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

Read more about cargo wasi usage in the guide!


This project is license under the Apache 2.0 license with the LLVM exception. See [LICENSE] for more details.


Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.

See the contributing section of the guide to start hacking on cargo wasi!


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