Instead of JSweet
JSweet alternatives
JSweet suits Java developers who want to build web and mobile HTML5 applications while keeping Java as their source language. It transpiles Java into TypeScript and JavaScript for browsers, mobile Web views, or Node.js, and says its generated programs are type-checked with Oracle's Java compiler and Microsoft's TypeScript compiler. JavaScript interoperability, support for more than 1,000 packaged libraries, browser debugging, and Eclipse, Maven, and Gradle plugins are useful when a project depends on JavaScript tools. JSweet is free, though setup calls for Git, Node.js, and Maven.
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SWC
Free plan AndroidAPILinux+3JavaScript and TypeScript build-tool authors — Unlike JSweet's Java-to-JavaScript transpilation, SWC compiles JavaScript and TypeScript and adds minification, WebAssembly transforms, and custom plugins.
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Transcrypt
Free plan LinuxMacSelf-hosted+2Python developers targeting browsers or Node.js — Transcrypt takes Python instead of Java and adds minification and multilevel sourcemaps for debugging generated JavaScript from Python source.
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Babel
Free plan APILinuxMac+2JavaScript projects needing syntax transforms — Babel transforms modern JavaScript, JSX, and type annotations, while JSweet translates Java and provides type-checked output.
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ClojureScript
Free plan LinuxMacSelf-hosted+2Clojure developers building browser or Node.js apps — ClojureScript compiles Clojure to JavaScript and adds Clojure data structures, macros, and REPL-based interactive development.
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Google Web Toolkit
Free plan ExtensionLinuxMac+2Java teams focused on AJAX browser applications — GWT also compiles Java, but generates browser-compliant JavaScript and HTML and offers deferred binding for browser-specific code.
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Kotlin/JS
Free plan LinuxMacWeb+1Kotlin teams sharing logic across clients and servers — Kotlin/JS compiles Kotlin and compatible dependencies to JavaScript, with code sharing across web, JVM, Android, and iOS projects.
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Opal
Free plan LinuxMacWeb+1Ruby developers sharing code across client and server — Opal compiles Ruby ahead of time to plain JavaScript and includes Ruby core and standard libraries rather than translating Java.
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Brython
Free plan AndroidiPhoneSelf-hosted+1 - 9
Cython
Free plan LinuxMacWindows - 10
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CoffeeScript
Free plan APILinuxMac+2 - 12
J2ObjC
Free plan iPhoneLinuxMac - 13
js_of_ocaml
Free plan APILinuxWeb - 14
Dart pub
Free plan LinuxMacWindows - 15
Scala.js
Free plan APILinuxMac+2 - 16
CodeTransEngine
Free plan APISelf-hosted - 17
Kalai
Free plan Self-hosted - 18
SourceMeld
Free plan APISelf-hosted - 19
Vala
Free plan LinuxMacWindows - 20
Mitosis
Free plan APIWeb - 21
Skulpt
Free plan Web - 22
Sucrase
Free plan APILinux - 23
ReScript
Free plan LinuxWeb - 24
The alternatives take different routes: some transform JavaScript, while others let teams write in Python, Clojure, Kotlin, or Ruby. GWT also accepts Java but focuses on browser applications. Before switching, weigh whether changing source language is acceptable, where the generated code must run, and whether you need features such as minification, source maps, REPLs, or JavaScript module support. Also compare each tool's integration and build approach with the libraries and workflow your project already uses.