Alternatives to Opal

Haxelib suits Haxe developers who need dependency management, repository publishing, or private and local libraries across desktop platforms.

Babel suits JavaScript developers who need to transform modern syntax for different browsers or environments, or build custom transformation pipelines.

ClojureScript

It suits Clojure developers building client or embedded applications for JavaScript environments.

It suits OCaml developers targeting browser or Node.js runtimes.

GWT suits Java developers building browser-based AJAX applications who want Java-to-JavaScript compilation and asynchronous server communication.

SWC

SWC suits developers and build-tool authors who need JavaScript or TypeScript compilation, minification, plugins, or WebAssembly transforms.

It suits Python developers building browser applications who want to use JavaScript libraries and browser APIs.

CoffeeScript

CoffeeScript suits developers who want to write source that compiles to JavaScript and use JavaScript libraries.

Cython suits Python developers building C extensions, wrapping external C libraries or embedding CPython in applications.

Educators, learners, and developers who need client-side Python execution or want to embed Python examples in webpages.

It suits developers sharing Java-based non-UI logic and data models with iOS applications who can work on the listed Mac toolchain.

Kotlin/JS

Kotlin/JS suits web developers who want to write frontends in Kotlin or share logic with JavaScript or TypeScript codebases.

It suits learners, educators, and developers who want browser-based TypeScript or JavaScript experiments without project setup.

Dart pub

It suits Dart developers managing dependencies for applications or publishing packages to pub.dev.

Scala.js

Scala.js suits Scala developers building applications for browsers, Node.js, or serverless environments who want to work with JavaScript libraries and APIs.