CINXE.COM
WebAssembly (Wasm) compilation | Dart
<!doctype html><html lang="en"><head><meta charset="utf-8"><meta http-equiv="x-ua-compatible" content="ie=edge"><meta name="viewport" content="width=device-width,initial-scale=1"><script>!function(e,t,a,n){e[n]=e[n]||[],e[n].push({"gtm.start":(new Date).getTime(),event:"gtm.js"});var g=t.getElementsByTagName(a)[0],m=t.createElement(a);m.async=!0,m.src="https://www.googletagmanager.com/gtm.js?id=GTM-5VSZM5J",g.parentNode.insertBefore(m,g)}(window,document,"script","dataLayer")</script><meta name="description" content="Learn how to compile your Dart web app to WebAssembly."><title>WebAssembly (Wasm) compilation | Dart</title><link rel="icon" sizes="64x64" href="/assets/img/logo/dart-64.png" eleventy:ignore><link href="/assets/img/touch-icon-iphone.png" rel="apple-touch-icon" eleventy:ignore><link href="/assets/img/touch-icon-ipad.png" rel="apple-touch-icon" sizes="152x152" eleventy:ignore><link href="/assets/img/touch-icon-iphone-retina.png" rel="apple-touch-icon" sizes="180x180" eleventy:ignore><link href="/assets/img/touch-icon-ipad-retina.png" rel="apple-touch-icon" sizes="167x167" eleventy:ignore><meta name="twitter:card" content="summary"><meta name="twitter:site" content="@dart_lang"><meta name="twitter:title" content="WebAssembly (Wasm) compilation"><meta name="twitter:description" content="Learn how to compile your Dart web app to WebAssembly."><meta property="og:title" content="WebAssembly (Wasm) compilation"><meta property="og:description" content="Learn how to compile your Dart web app to WebAssembly."><meta property="og:url" content="/web/wasm/"><meta property="og:image" content="/assets/img/logo/dart-logo-for-shares.png?2" eleventy:ignore><link rel="preconnect" href="https://fonts.googleapis.com"><link rel="preconnect" href="https://fonts.gstatic.com" crossorigin><link href="https://fonts.googleapis.com/css2?family=Google+Sans:wght@400;500;700&display=swap" rel="stylesheet"><link href="https://fonts.googleapis.com/css2?family=Google+Sans+Display:wght@400&display=swap" rel="stylesheet"><link href="https://fonts.googleapis.com/css2?family=Google+Sans+Mono:wght@400;500;700&display=swap" rel="stylesheet"><link href="https://fonts.googleapis.com/css2?family=Google+Sans+Text:wght@400;500;700&display=swap" rel="stylesheet"><link href="https://fonts.googleapis.com/css2?family=Material+Symbols+Outlined:opsz,wght,FILL,GRAD@24,400,0..1,0" rel="stylesheet"><link rel="stylesheet" href="/assets/css/main.css?v=3"><script src="/assets/js/os-tabs.js?v=3"></script><script src="/assets/js/main.js?v=3"></script><script>!function(e,a,t,n,c,o,s){e.GoogleAnalyticsObject=c,e[c]=e[c]||function(){(e[c].q=e[c].q||[]).push(arguments)},e[c].l=1*new Date,o=a.createElement(t),s=a.getElementsByTagName(t)[0],o.async=1,o.src="//www.google-analytics.com/analytics.js",s.parentNode.insertBefore(o,s)}(window,document,"script",0,"ga"),ga("create","UA-26406144-4","auto"),ga("send","pageview")</script></head><body class="default.html"><a id="skip-to-main" class="filled-button" href="#site-content-title" tabindex="1">Skip to main content</a><section id="cookie-notice"><div class="container"><p>dart.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic.</p><div class="button-group"><a class="text-button" href="https://policies.google.com/technologies/cookies" target="_blank" rel="noopener">Learn more</a> <button id="cookie-consent" class="filled-button">OK, got it</button></div></div></section><noscript><iframe src="https://www.googletagmanager.com/ns.html?id=GTM-5VSZM5J" height="0" width="0" style="display:none;visibility:hidden"></iframe></noscript><div id="site-banner" role="alert"><p>Announcing Dart 3.7! Find out about updates to the language, analyzer, pub.dev, and more, in the <a href="https://medium.com/dartlang/announcing-dart-3-7-bf864a1b195c" target="_blank">blog post</a>.</p></div><header id="site-header"><nav id="mainnav"><div id="menu-toggle"><span class="material-symbols" title="Toggle side navigation menu." aria-label="Toggle side navigation menu." type="button">menu</span></div><a href="/" class="brand" title="Dart"><img src="/assets/img/logo/logo-white-text.svg" alt="Dart"></a><ul class="navbar"><li><a href="/overview" class="nav-link">Overview</a></li><li class="mainnav__get-started"><a href="/docs" class="nav-link active"><span>Docs</span></a></li><li><a href="/community" class="nav-link">Community</a></li><li><a href="/#try-dart" class="nav-link">Try Dart</a></li><li><a href="/get-dart" class="nav-link">Get Dart</a></li><li class="searchfield"><form action="/search" class="site-header-search form-inline" id="cse-search-box"><input type="hidden" name="cx" value="011220921317074318178:_yy-tmb5t_i"> <input type="hidden" name="ie" value="UTF-8"> <input type="hidden" name="hl" value="en"> <input class="site-header-searchfield form-control search-field" type="search" name="q" id="search-main" autocomplete="off" placeholder="Search" aria-label="Search"></form></li></ul></nav></header><div id="site-below-header"><div id="site-main-row"><div id="sidenav"><form action="/search/" class="site-header-search form-inline"><input class="site-header-searchfield form-control search-field" type="search" name="q" id="search-side" autocomplete="off" placeholder="Search" aria-label="Search"></form><ul class="navbar-nav"><li aria-hidden="true"><div class="sidenav-divider"></div></li><li class="nav-item"><a href="/overview" class="nav-link">Overview</a></li><li class="nav-item"><a href="/community" class="nav-link">Community</a></li><li class="nav-item"><a href="https://dartpad.dev" class="nav-link">Try Dart</a></li><li class="nav-item"><a href="/get-dart" class="nav-link">Get Dart</a></li><li class="nav-item"><a href="/docs" class="nav-link">Docs</a></li><li aria-hidden="true"><div class="sidenav-divider"></div></li></ul><ul class="nav"><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-1" role="button" aria-expanded="false" aria-controls="-sidenav-1"><span>Language</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1"><li class="nav-item"><a class="nav-link" href="/language"><div><span>Introduction</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-2" role="button" aria-expanded="false" aria-controls="-sidenav-1-2"><span>Syntax basics</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-2"><li class="nav-item"><a class="nav-link" href="/language/variables"><div><span>Variables</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/operators"><div><span>Operators</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/comments"><div><span>Comments</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/metadata"><div><span>Metadata</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/libraries"><div><span>Libraries & imports</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/keywords"><div><span>Keywords</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-3" role="button" aria-expanded="false" aria-controls="-sidenav-1-3"><span>Types</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-3"><li class="nav-item"><a class="nav-link" href="/language/built-in-types"><div><span>Built-in types</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/records"><div><span>Records</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/collections"><div><span>Collections</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/generics"><div><span>Generics</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/typedefs"><div><span>Typedefs</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/type-system"><div><span>Type system</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-4" role="button" aria-expanded="false" aria-controls="-sidenav-1-4"><span>Patterns</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-4"><li class="nav-item"><a class="nav-link" href="/language/patterns"><div><span>Overview & usage</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/pattern-types"><div><span>Pattern types</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://codelabs.developers.google.com/codelabs/dart-patterns-records" target="_blank" rel="noopener"><div><span>Applied tutorial</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/language/functions"><div><span>Functions</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-6" role="button" aria-expanded="false" aria-controls="-sidenav-1-6"><span>Control flow</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-6"><li class="nav-item"><a class="nav-link" href="/language/loops"><div><span>Loops</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/branches"><div><span>Branches</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/error-handling"><div><span>Error handling</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-7" role="button" aria-expanded="false" aria-controls="-sidenav-1-7"><span>Classes & objects</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-7"><li class="nav-item"><a class="nav-link" href="/language/classes"><div><span>Classes</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/constructors"><div><span>Constructors</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/methods"><div><span>Methods</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/extend"><div><span>Extend a class</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/mixins"><div><span>Mixins</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/enums"><div><span>Enums</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/extension-methods"><div><span>Extension methods</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/extension-types"><div><span>Extension types</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/callable-objects"><div><span>Callable objects</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-8" role="button" aria-expanded="false" aria-controls="-sidenav-1-8"><span>Class modifiers</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-8"><li class="nav-item"><a class="nav-link" href="/language/class-modifiers"><div><span>Overview & usage</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/class-modifiers-for-apis"><div><span>Class modifiers for API maintainers</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/modifier-reference"><div><span>Reference</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-9" role="button" aria-expanded="false" aria-controls="-sidenav-1-9"><span>Concurrency</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-9"><li class="nav-item"><a class="nav-link" href="/language/concurrency"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/async"><div><span>Asynchronous support</span></div></a></li><li class="nav-item"><a class="nav-link" href="/language/isolates"><div><span>Isolates</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-1-10" role="button" aria-expanded="false" aria-controls="-sidenav-1-10"><span>Null safety</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-1-10"><li class="nav-item"><a class="nav-link" href="/null-safety"><div><span>Sound null safety</span></div></a></li><li class="nav-item"><a class="nav-link" href="/null-safety/migration-guide"><div><span>Migrating to null safety</span></div></a></li><li class="nav-item"><a class="nav-link" href="/null-safety/understanding-null-safety"><div><span>Understanding null safety</span></div></a></li><li class="nav-item"><a class="nav-link" href="/null-safety/unsound-null-safety"><div><span>Unsound null safety</span></div></a></li><li class="nav-item"><a class="nav-link" href="/null-safety/faq"><div><span>FAQ</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-2" role="button" aria-expanded="false" aria-controls="-sidenav-2"><span>Core libraries</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-2"><li class="nav-item"><a class="nav-link" href="/libraries"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/dart-core"><div><span>dart:core</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/dart-async"><div><span>dart:async</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/dart-math"><div><span>dart:math</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/dart-convert"><div><span>dart:convert</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/dart-io"><div><span>dart:io</span></div></a></li><li class="nav-item"><a class="nav-link" href="/interop/js-interop"><div><span>dart:js_interop</span></div></a></li><div class="sidenav-divider"></div><li class="nav-item"><a class="nav-link" href="/libraries/collections/iterables"><div><span>Iterable collections</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-2-10" role="button" aria-expanded="false" aria-controls="-sidenav-2-10"><span>Asynchronous programming</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-2-10"><li class="nav-item"><a class="nav-link" href="/libraries/async/async-await"><div><span>Tutorial</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/async/futures-error-handling"><div><span>Futures and error handling</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/async/using-streams"><div><span>Using streams</span></div></a></li><li class="nav-item"><a class="nav-link" href="/libraries/async/creating-streams"><div><span>Creating streams</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-3" role="button" aria-expanded="false" aria-controls="-sidenav-3"><span>Effective Dart</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-3"><li class="nav-item"><a class="nav-link" href="/effective-dart"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/effective-dart/style"><div><span>Style</span></div></a></li><li class="nav-item"><a class="nav-link" href="/effective-dart/documentation"><div><span>Documentation</span></div></a></li><li class="nav-item"><a class="nav-link" href="/effective-dart/usage"><div><span>Usage</span></div></a></li><li class="nav-item"><a class="nav-link" href="/effective-dart/design"><div><span>Design</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-4" role="button" aria-expanded="false" aria-controls="-sidenav-4"><span>Packages</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-4"><li class="nav-item"><a class="nav-link" href="/tools/pub/packages"><div><span>How to use packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/useful-packages"><div><span>Commonly used packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/create-packages"><div><span>Creating packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/publishing"><div><span>Publishing packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/writing-package-pages"><div><span>Writing package pages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/workspaces"><div><span>Workspaces (monorepo support)</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-4-7" role="button" aria-expanded="false" aria-controls="-sidenav-4-7"><span>Package reference</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-4-7"><li class="nav-item"><a class="nav-link" href="/tools/pub/dependencies"><div><span>Dependencies</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/glossary"><div><span>Glossary</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/package-layout"><div><span>Package layout conventions</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/environment-variables"><div><span>Pub environment variables</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/pubspec"><div><span>Pubspec file</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/troubleshoot"><div><span>Troubleshooting pub</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/verified-publishers"><div><span>Verified publishers</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/security-advisories"><div><span>Security advisories</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/versioning"><div><span>Versioning</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/custom-package-repositories"><div><span>Custom package repositories</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/tools/pub/private-files"><div><span>What not to commit</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link active collapsible" data-toggle="collapse" data-target="#-sidenav-5" role="button" aria-expanded="true" aria-controls="-sidenav-5"><span>Development</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse show" id="-sidenav-5"><li class="nav-item"><a class="nav-link" href="/libraries/serialization/json"><div><span>JSON serialization</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/language/number-representation"><div><span>Number representation</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/google-apis"><div><span>Google APIs</span></div></a></li><li class="nav-item"><a class="nav-link" href="/multiplatform-apps"><div><span>Multi-platform apps</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-5-5" role="button" aria-expanded="false" aria-controls="-sidenav-5-5"><span>Command-line & server apps</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-5-5"><li class="nav-item"><a class="nav-link" href="/server"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/get-started"><div><span>Get started</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/cmdline"><div><span>Write command-line apps</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/fetch-data"><div><span>Fetch data from the internet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials/server/httpserver"><div><span>Write HTTP servers</span></div></a></li><li class="nav-item"><a class="nav-link" href="/server/libraries"><div><span>Libraries & packages</span></div></a></li><li class="nav-item"><a class="nav-link" href="/server/google-cloud"><div><span>Google Cloud</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link active collapsible" data-toggle="collapse" data-target="#-sidenav-5-6" role="button" aria-expanded="true" aria-controls="-sidenav-5-6"><span>Web apps</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse show" id="-sidenav-5-6"><li class="nav-item"><a class="nav-link" href="/web"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/web/get-started"><div><span>Get started</span></div></a></li><li class="nav-item"><a class="nav-link" href="/web/deployment"><div><span>Deployment</span></div></a></li><li class="nav-item"><a class="nav-link" href="/web/libraries"><div><span>Libraries & packages</span></div></a></li><li class="nav-item"><a class="nav-link active" href="/web/wasm"><div><span>Wasm compilation</span></div></a></li></ul></li><li class="nav-item"><a class="nav-link" href="/libraries/core/environment-declarations"><div><span>Environment declarations</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-6" role="button" aria-expanded="false" aria-controls="-sidenav-6"><span>Interoperability</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-6"><li class="nav-item"><a class="nav-link" href="/interop/c-interop"><div><span>C interop</span></div></a></li><li class="nav-item"><a class="nav-link" href="/interop/objective-c-interop"><div><span>Objective-C & Swift interop</span></div></a></li><li class="nav-item"><a class="nav-link" href="/interop/java-interop"><div><span>Java & Kotlin interop</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-6-4" role="button" aria-expanded="false" aria-controls="-sidenav-6-4"><span>JavaScript interop</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-6-4"><li class="nav-item"><a class="nav-link" href="/interop/js-interop"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/interop/js-interop/usage"><div><span>Usage</span></div></a></li><li class="nav-item"><a class="nav-link" href="/interop/js-interop/js-types"><div><span>JS types</span></div></a></li><li class="nav-item"><a class="nav-link" href="/interop/js-interop/tutorials"><div><span>Tutorials</span></div></a></li><li class="nav-item"><a class="nav-link" href="/interop/js-interop/past-js-interop"><div><span>Past JS interop</span></div></a></li><div class="sidenav-divider"></div><li class="nav-item"><a class="nav-link" href="/interop/js-interop/package-web"><div><span>Web interop</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-7" role="button" aria-expanded="false" aria-controls="-sidenav-7"><span>Tools & techniques</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-7"><li class="nav-item"><a class="nav-link" href="/tools"><div><span>Overview</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-7-2" role="button" aria-expanded="false" aria-controls="-sidenav-7-2"><span>Editors & debuggers</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-7-2"><li class="nav-item"><a class="nav-link" href="/tools/jetbrains-plugin"><div><span>IntelliJ & Android Studio</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/vs-code"><div><span>VS Code</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-devtools"><div><span>Dart DevTools</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-7-2-4" role="button" aria-expanded="false" aria-controls="-sidenav-7-2-4"><span>DartPad</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-7-2-4"><li class="nav-item"><a class="nav-link" href="/tools/dartpad"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dartpad/troubleshoot"><div><span>Troubleshooting DartPad</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-7-3" role="button" aria-expanded="false" aria-controls="-sidenav-7-3"><span>Command-line tools</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-7-3"><li class="nav-item"><button class="nav-link collapsible" data-toggle="collapse" data-target="#-sidenav-7-3-1" role="button" aria-expanded="true" aria-controls="-sidenav-7-3-1"><span>Dart SDK</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse show" id="-sidenav-7-3-1"><li class="nav-item"><a class="nav-link" href="/tools/sdk"><div><span>Overview</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-tool"><div><span>dart</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-analyze"><div><span>dart analyze</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-compile"><div><span>dart compile</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-create"><div><span>dart create</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-doc"><div><span>dart doc</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-fix"><div><span>dart fix</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-format"><div><span>dart format</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-info"><div><span>dart info</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/pub/cmd"><div><span>dart pub</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-run"><div><span>dart run</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dart-test"><div><span>dart test</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/dartaotruntime"><div><span>dartaotruntime</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/experiment-flags"><div><span>Experiment flags</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible" data-toggle="collapse" data-target="#-sidenav-7-3-2" role="button" aria-expanded="true" aria-controls="-sidenav-7-3-2"><span>Other command-line tools</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse show" id="-sidenav-7-3-2"><li class="nav-item"><a class="nav-link" href="/tools/build_runner"><div><span>build_runner</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/webdev"><div><span>webdev</span></div></a></li></ul></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-7-4" role="button" aria-expanded="false" aria-controls="-sidenav-7-4"><span>Static analysis</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-7-4"><li class="nav-item"><a class="nav-link" href="/tools/analysis"><div><span>Customizing static analysis</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/non-promotion-reasons"><div><span>Fixing type promotion failures</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/linter-rules"><div><span>Linter rules</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tools/diagnostic-messages"><div><span>Diagnostic messages</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-7-5" role="button" aria-expanded="false" aria-controls="-sidenav-7-5"><span>Testing & optimization</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-7-5"><li class="nav-item"><a class="nav-link" href="/tools/testing"><div><span>Testing</span></div></a></li><li class="nav-item"><a class="nav-link" href="/web/debugging"><div><span>Debugging web apps</span></div></a></li></ul></li></ul></li><li aria-hidden="true"><div class="sidenav-divider"></div></li><li class="nav-item"><button class="nav-link collapsed collapsible" data-toggle="collapse" data-target="#-sidenav-9" role="button" aria-expanded="false" aria-controls="-sidenav-9"><span>Resources</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-9"><li class="nav-item"><a class="nav-link" href="/resources/dart-cheatsheet"><div><span>Language cheatsheet</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/breaking-changes"><div><span>Breaking changes</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/language/evolution"><div><span>Language evolution</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/language/spec"><div><span>Language specification</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/dart-3-migration"><div><span>Dart 3 migration guide</span></div></a></li><li class="nav-item"><button class="nav-link collapsible collapsed" data-toggle="collapse" data-target="#-sidenav-9-6" role="button" aria-expanded="false" aria-controls="-sidenav-9-6"><span>Coming from ...</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse" id="-sidenav-9-6"><li class="nav-item"><a class="nav-link" href="/resources/coming-from/js-to-dart"><div><span>JavaScript to Dart</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/coming-from/swift-to-dart"><div><span>Swift to Dart</span></div></a></li></ul></li><div class="sidenav-divider"></div><li class="nav-item"><a class="nav-link" href="/resources/faq"><div><span>FAQ</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/glossary"><div><span>Glossary</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/books"><div><span>Books</span></div></a></li><li class="nav-item"><a class="nav-link" href="/resources/videos"><div><span>Videos</span></div></a></li><li class="nav-item"><a class="nav-link" href="/tutorials"><div><span>Tutorials</span></div></a></li></ul></li><li class="nav-item"><button class="nav-link collapsible" data-toggle="collapse" data-target="#-sidenav-10" role="button" aria-expanded="true" aria-controls="-sidenav-10"><span>Related sites</span> <span class="material-symbols expander" aria-hidden="true">expand_more</span></button><ul class="nav collapse show" id="-sidenav-10"><li class="nav-item"><a class="nav-link" href="https://api.dart.dev" target="_blank" rel="noopener"><div><span>API reference</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://medium.com/dartlang" target="_blank" rel="noopener"><div><span>Blog</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://dartpad.dev" target="_blank" rel="noopener"><div><span>DartPad (online editor)</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://flutter.dev" target="_blank" rel="noopener"><div><span>Flutter</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li><li class="nav-item"><a class="nav-link" href="https://pub.dev" target="_blank" rel="noopener"><div><span>Package site</span><span class="material-symbols" aria-hidden="true">open_in_new</span></div></a></li></ul></li></ul></div><main id="page-content"><div id="site-toc--side" class="site-toc"><header class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry nav-item"><a class="nav-link" href="#webassembly-support">WebAssembly support</a><ul class="nav"><li class="toc-entry nav-item"><a class="nav-link" href="#supported-packages">Supported packages</a></li></ul></li><li class="toc-entry nav-item"><a class="nav-link" href="#compiling-to-wasm">Compiling your web app to Wasm</a></li></ul></div><article><div class="content"><div id="site-content-title"><h1>WebAssembly (Wasm) compilation</h1></div><div id="site-toc--inline" class="site-toc"><header class="site-toc__title">Contents</header><ul class="section-nav"><li class="toc-entry"><a href="#webassembly-support">WebAssembly support</a><ul><li class="toc-entry"><a href="#supported-packages">Supported packages</a></li></ul></li><li class="toc-entry"><a href="#compiling-to-wasm">Compiling your web app to Wasm</a></li></ul></div><p>The Dart team is excited to add <a href="https://webassembly.org/">WebAssembly</a> as a compilation target when building Dart and <a href="https://flutter.dev/wasm">Flutter</a> applications for the web.</p><p>Development of WebAssembly support remains ongoing, which will potentially result in frequent changes. Revisit this page for the latest updates.</p><aside class="alert alert-info"><div class="alert-header"><span class="material-symbols" aria-hidden="true">info</span> <span>Note</span></div><div class="alert-content"><p><strong>Support for Wasm is now in stable!</strong></p><p>WebAssembly support for Dart web is available on the Dart <em>stable</em> <a href="/get-dart#release-channels">channel</a>.</p></div></aside><div class="header-wrapper"><h2 id="webassembly-support">WebAssembly support</h2><a class="heading-link" href="#webassembly-support" aria-label="Link to 'WebAssembly support' section">#</a></div><p>The current version of Dart compilation to WebAssembly has a number of restrictions:</p><ol><li><p>It targets WebAssembly with Garbage Collection (<a href="https://developer.chrome.com/blog/wasmgc/">WasmGC</a>), so not all browsers are currently supported. The current list of browsers is available in the <a href="https://flutter.dev/wasm">Flutter documentation</a>.</p></li><li><p>The compiled Wasm output currently targets JavaScript environments (such as browsers), and thus currently doesn't support execution in standard Wasm run-times like wasmtime and wasmer. For details, see <a href="https://github.com/dart-lang/sdk/issues/53884">issue #53884</a></p></li><li><p>Only Dart's <a href="/interop/js-interop/">next-gen JS interop mechanism</a> is supported when compiling to Wasm.</p></li><li><p>There is currently no support in the <code>webdev</code> tool for running (<code>webdev serve</code>) or building (<code>webdev build</code>). The steps below contain a temporary workaround. For details, see <a href="https://github.com/dart-lang/webdev/issues/2296">webdev issue 2206</a>.</p></li></ol><div class="header-wrapper"><h3 id="supported-packages">Supported packages</h3><a class="heading-link" href="#supported-packages" aria-label="Link to 'Supported packages' section">#</a></div><p>To find Wasm-compatible packages, use the <a href="https://pub.dev/packages?q=is%3Awasm-ready"><code>wasm-ready</code></a> filter on <a href="https://pub.dev">pub.dev</a>.</p><p>A package is "wasm-ready" if it doesn't import non-Wasm compliant libraries like <code>dart:html</code>, <code>dart:js</code>, etc. You can find the full list of unallowed libraries on the <a href="/interop/js-interop/#next-generation-js-interop">JS interop page</a>.</p><div class="header-wrapper"><h2 id="compiling-to-wasm">Compiling your web app to Wasm</h2><a class="heading-link" href="#compiling-to-wasm" aria-label="Link to 'Compiling your web app to Wasm' section">#</a></div><p>We've landed support in the <code>dart</code> CLI for invoking the Wasm compiler in Dart and <a href="https://flutter.dev/wasm">Flutter</a>:</p><div class="code-block-wrapper language-console"><div class="code-block-body"><pre class="shiki dash-light" tabindex="0"><code><span class="line"><span style="color:#222222">$ dart help compile wasm</span></span> <span class="line"><span style="color:#222222">Compile Dart to a WebAssembly/WasmGC module.</span></span> <span class="line"></span> <span class="line"><span style="color:#222222">Usage: dart compile wasm [arguments] <dart entry point></span></span> <span class="line"><span style="color:#222222">-h, --help Print this usage information.</span></span> <span class="line"><span style="color:#222222">-o, --output Write the output to <file name>.</span></span> <span class="line"><span style="color:#222222"> This can be an absolute or relative path.</span></span> <span class="line"><span style="color:#222222">-v, --verbose Print debug output during compilation</span></span> <span class="line"><span style="color:#222222"> --enable-asserts Enable assert statements.</span></span> <span class="line"><span style="color:#222222">-D, --define=<key=value> Define an environment declaration. To specify multiple declarations, use multiple</span></span> <span class="line"><span style="color:#222222"> options or use commas to separate key-value pairs.</span></span> <span class="line"><span style="color:#222222"> For example: dart compile wasm -Da=1,b=2 main.dart</span></span></code></pre></div></div><p>Wasm compilation is available in stable, but still in preview. While we continue optimizing tooling to improve developer experience, you can try compiling Dart to Wasm today by following the temporary steps outlined here:</p><ol><li><p>Start with a web app: <code>dart create -t web mywebapp</code></p><p>The template creates a small web app using <a href="https://pub.dev/packages/web"><code>package:web</code></a>, which is necessary to run Wasm. Make sure your web apps are <a href="/interop/js-interop/package-web/">migrated</a> from <code>dart:html</code> to <code>package:web</code>.</p></li><li><p>Compile with Wasm to a new <code>site</code> output directory: <code>mywebapp$ dart compile wasm web/main.dart -o site/main.wasm</code></p></li><li><p>Copy over the web files: <code>cp web/index.html web/styles.css site/</code></p></li><li><p>Create a JS bootstrap file to load the Wasm code:</p><p>Add a new file <code>site/main.dart.js</code> and fill it with the contents of this <a href="https://gist.github.com/mit-mit/0fcb1247a9444b0cadf611aa5fc6f32e"><code>main.dart.js</code> sample</a>.</p></li><li><p>Serve the output: <code>dart pub global run dhttpd</code> (<a href="https://pub.dev/packages/dhttpd">docs</a>)</p></li></ol><p>You can also try out this small example <a href="https://github.com/mit-mit/sandbox">here</a>.</p><p id="page-github-links"><span>Unless stated otherwise, the documentation on this site reflects Dart 3.7.1. Page last updated on 2024-06-17.</span> <a href="https://github.com/dart-lang/site-www/tree/main/src/content/web/wasm.md" target="_blank" rel="noopener">View source</a> <span>or </span><a href="https://github.com/dart-lang/site-www/issues/new?template=1_page_issue.yml&page-url=https://dart.dev/web/wasm/&page-source=https://github.com/dart-lang/site-www/tree/main/src/content/web/wasm.md" title="Report an issue with this page" target="_blank" rel="noopener">report an issue</a>.</p></div></article></main></div><footer id="page-footer"><div class="footer-section footer-main"><a href="/" class="brand" title="Dart"><img src="/assets/img/logo/logo-white-text.svg" alt="Dart" width="164"></a><div class="footer-social-links"><a href="https://medium.com/dartlang" target="_blank" rel="noopener" title="Dart's Medium publication"><svg><use href="/assets/img/social/medium.svg#medium"></use></svg> </a><a href="https://github.com/dart-lang" target="_blank" rel="noopener" title="Dart's GitHub organization"><svg><use href="/assets/img/social/github.svg#github"></use></svg> </a><a href="https://bsky.app/profile/dart.dev" target="_blank" rel="noopener" title="Dart's Bluesky profile"><svg><use href="/assets/img/social/bluesky.svg#bluesky"></use></svg> </a><a href="https://twitter.com/dart_lang" target="_blank" rel="noopener" title="Dart's X (Twitter) profile"><svg><use href="/assets/img/social/x.svg#x"></use></svg></a></div></div><div class="footer-section footer-tray"><div class="footer-licenses">Except as otherwise noted, this site is licensed under a <a href="https://creativecommons.org/licenses/by/4.0/">Creative Commons Attribution 4.0 International License</a>, and code samples are licensed under the <a href="https://opensource.org/licenses/BSD-3-Clause">3-Clause BSD License</a>.</div><div class="footer-utility-links"><ul><li><a href="/terms" title="Terms of use">Terms</a></li><li><a href="https://policies.google.com/privacy" target="_blank" rel="noopener" title="Privacy policy">Privacy</a></li><li><a href="/security" title="Security philosophy and practices">Security</a></li></ul></div></div></footer></div></body></html>