Welcome to the SwiftWasm Documentation!

SwiftWasm is an open source project to support the WebAssembly target for Swift.

The goal of this project is to fully support the WebAssembly target for Swift and to be merged into the upstream repository.

Getting Started (with Nightly Toolchain)


You can install latest toolchain of SwiftWasm from Release Page

The toolchains can be installed via swiftenv like official nightly toolchain.


$ swiftenv install \
$ swift --version
Swift version 5.3-dev (LLVM 7fc8796bc1, Swift 5be35e7aee)
Target: x86_64-apple-darwin19.3.0

Hello, World!

$ echo 'print("Hello, world!")' > hello.swift
# Compile Swift code into WebAssembly with WASI
$ TOOLCHAIN_PATH=$(dirname $(swiftenv which swiftc))/../
$ swiftc \
    -target wasm32-unknown-wasi \
    -sdk $TOOLCHAIN_PATH/share/wasi-sysroot \
    hello.swift -o hello.wasm

You can the run the produced binary with wasmer (or other WebAssembly runtime):

$ wasmer hello.wasm

The produced binary depends on WASI which is an interface of system call for WebAssembly. So you need to use WASI supported runtime and when you run the binary on browser, you need WASI polyfill library like @wasmer/wasi.

Swift Package Manager

You can also use SwiftPM for managing packages in the same way as other platforms.

$ swiftenv local wasm-DEVELOPMENT-SNAPSHOT-2020-06-07-a
$ swift package init --type executable
$ swift build --triple wasm32-unknown-wasi
$ wasmer ./.build/debug/hello-swiftwasm
Hello, world!

JavaScript Bindings

JavaScriptKit is Swift framework to interact with JavaScript through WebAssembly.

You can use any JavaScript API from Swift using this library.