Learn SWIFT-WASM with Real Code Examples

SwiftWasm compiles Swift source code into WebAssembly using a specialized fork of the Swift compiler.

It enables running Swift apps inside browsers and headless WASI runtimes.

Supports JavaScript interop for DOM access and Web APIs.

Allows building serverless WebAssembly microservices using Swift.

Makes Swift viable beyond Apple platforms by targeting Wasm.

Swift compiler backend targeting Wasm32

Interop with JavaScript using the JavaScriptKit library

Standard library subset adapted for WebAssembly

WASI compatibility for command-line apps

SwiftPM support for dependency management

Wasm module -> compiled Swift program

JavaScriptKit -> interop for browser APIs

WASI -> Swift CLI runtime for Wasm environments

SwiftPM -> dependency management

async/await -> event-driven browser logic

Sources/ - application code

Package.swift - dependencies

index.html - browser loader for wasm

main.wasm - compiled Swift output

carton configuration for development server

Write Swift code

Compile to Wasm with SwiftWasm or carton

Bind to JS environment using JavaScriptKit

Serve via development server

Run in browser/WASI and iterate

Beginner: simple DOM text change using JS interop

Intermediate: Swift async/await browser app

Advanced: Swift graphics/game in browser

Expert: edge microservice with SwiftWasm

Auditor: security review of Wasm Swift modules

SwiftWasm vs Rust/Wasm: easier syntax, smaller ecosystem

SwiftWasm vs AssemblyScript: more powerful language

SwiftWasm vs TinyGo: bigger binaries, richer language

SwiftWasm vs C/C++ Emscripten: safer memory model

SwiftWasm vs JavaScript: faster compute, static types

2019 – Project begins

2020 – JavaScriptKit introduced

2021 – Carton dev tooling

2022 – WASI improvements and Swift 5.6 support

2023–2025 – Performance improvements and community expansion

SwiftWasm - Swift toolchain for wasm

JavaScriptKit - JS interop library

WASI - WebAssembly System Interface

Carton - SwiftWasm dev server tool

Wasm binary - final output file