Best Kotlin/JS Alternatives in 2026
The top Kotlin/JS alternatives are Babel, SWC and Cython: 15 code transpilers our editors would look at instead of Kotlin/JS, in our ranking order.
Kotlin/JS: A free Kotlin-to-JavaScript toolchain for browser and Node.js projects. Where it falls short: requires kotlin code and compatible dependencies as input.
Switching from Kotlin/JS? For most code transpilers buyers the best Kotlin/JS alternative is Babel, built for javaScript projects needing flexible transforms. Fable offers the most source languages (1 languages).
Why People Look for a Kotlin/JS Alternative
- Requires Kotlin code and compatible dependencies as input
- Projects are configured through the Kotlin Multiplatform Gradle plugin
- Support channels are community resources and documentation
Quick Picks by What You Need
- Best overallBabel9.3
JavaScript projects needing flexible transforms
Visit Babel - Best free optionBabel9.3
Has a free plan
Visit Babel - Most source languagesFable8.1
1 languages
Visit Fable
All 15 Kotlin/JS Alternatives, Ranked
Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.
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Best forJavaScript projects needing flexible transforms
- Better than Kotlin/JS:
- Editor score 9.3 vs 8.8
Flexible ECMAScript transforms with CLI, Node.js APIs, and browser compilation.
- Syntax-version conversion
- Intermediate output
- API access
9.3/10★★★★★Visit Babel -
Best forFast JavaScript and TypeScript build pipelines
- Better than Kotlin/JS:
- Editor score 9.2 vs 8.8
An open-source compiler with minification and bundling for JavaScript and TypeScript workflows.
9.2/10★★★★★Visit SWC -
Best forPython projects needing C or C++ extensions
An open-source compiler for Python projects that need native C or C++ extensions.
- API access
- CLI access
8.7/10★★★★☆Visit Cython -
Best forJava teams targeting JavaScript or WebAssembly
A free, open-source compiler for Java teams building browser applications or native targets.
- API access
- CLI access
8.6/10★★★★☆Visit TeaVM -
Best forJava teams building browser applications
A Java-based route to browser applications, with compilation, widgets and testing tools.
- API access
- CLI access
8.5/10★★★★☆Visit GWT -
Best forClojure teams targeting browser and Node.js
An open-source Clojure-to-JavaScript compiler with browser and Node.js targets.
- API access
- CLI access
8.4/10★★★★☆Visit ClojureScript -
Best forScala teams building JavaScript applications
An open-source Scala-to-JavaScript toolchain with incremental builds and JavaScript interoperability.
- Intermediate output
- API access
- CLI access
8.3/10★★★★☆Visit Scala.js -
Best forTyped JavaScript teams wanting ReScript
ReScript adds static typing to JavaScript projects and compiles to readable JavaScript.
- CLI access
8.2/10★★★★☆Visit ReScript -
Best forF# teams targeting several languages
A self-hosted F# compiler with seven listed output targets and CLI workflows.
- CLI access
8.1/10★★★★☆Visit Fable -
Best forSmall teams removing types and JSX from JavaScript
A free, focused transpiler for TypeScript, JSX and Flow in development workflows.
8.0/10★★★★☆Visit Sucrase -
Best forJava teams targeting TypeScript and JavaScript
An open-source Java-to-web transpiler for teams that want to keep Java syntax and tooling.
- Syntax-version conversion
- Intermediate output
- CLI access
7.9/10★★★★☆Visit JSweet -
Best forPython developers targeting browsers or Node.js
A free, open-source Python-to-JavaScript compiler with CLI builds and debugging support.
- CLI access
7.8/10★★★★☆Visit Transcrypt -
Best forCoffeeScript users needing JavaScript output
A concise alternative syntax for producing modern JavaScript, with CLI, REPL, and API access.
- Syntax-version conversion
- Intermediate output
- API access
7.7/10★★★★☆Visit CoffeeScript -
Best forRuby developers bringing code to JavaScript
A free, open-source compiler for bringing Ruby code into JavaScript projects.
- API access
- CLI access
7.6/10★★★★☆Visit Opal -
Best forTeams generating components for multiple frameworks
An open-source JSX component compiler for generating code across frameworks.
- Intermediate output
- CLI access
7.5/10★★★★☆Visit Mitosis
Kotlin/JS Alternatives: Common Questions
What is the best alternative to Kotlin/JS?
Babel: #1 in our Code Transpilers ranking, with an editor score of 9.3 out of 10. Flexible ECMAScript transforms with CLI, Node.js APIs, and browser compilation.
Is there a free alternative to Kotlin/JS?
Yes. Babel, SWC, Cython, TeaVM and Google Web Toolkit have a free plan or a free tier (15 of the 15 alternatives on this page).
Why do people look for Kotlin/JS alternatives?
Requires Kotlin code and compatible dependencies as input; Projects are configured through the Kotlin Multiplatform Gradle plugin; Support channels are community resources and documentation.
Which Kotlin/JS alternative has the most source languages?
Fable, with 1 languages.
How do I switch from Kotlin/JS?
Export your data from Kotlin/JS (most tools have an export in their settings). Sign up for the alternative; start on its free plan or trial if it has one. Import your export and set up the integrations your team relies on. Run both side by side for a short while, then cancel Kotlin/JS.
How to Switch from Kotlin/JS
- Export your data from Kotlin/JS (most tools have an export in their settings).
- Sign up for the alternative; start on its free plan or trial if it has one.
- Import your export and set up the integrations your team relies on.
- Run both side by side for a short while, then cancel Kotlin/JS.
Kotlin/JS vs Each Alternative
| # | Tool | Free plan | Paid from | Intermediate output | API access | Score |
|---|---|---|---|---|---|---|
| 3 | Kotlin/JS | Yes | Free | Yes | 8.8 | |
| 1 | Babel | Yes | Free | Yes | Yes | 9.3 |
| 2 | SWC | Yes | Free | 9.2 | ||
| 3 | Cython | Yes | Free | No | Yes | 8.7 |
| 4 | TeaVM | Yes | Free | Yes | 8.6 | |
| 5 | Google Web Toolkit | Yes | Free | Yes | 8.5 | |
| 6 | ClojureScript | Free | Yes | 8.4 | ||
| 7 | Scala.js | Free | Yes | Yes | 8.3 | |
| 8 | ReScript | Free | 8.2 | |||
| 9 | Fable | Free | 8.1 | |||
| 10 | Sucrase | Yes | Free | 8.0 | ||
| 11 | JSweet | Free | Yes | 7.9 | ||
| 12 | Transcrypt | Yes | Free | No | 7.8 | |
| 13 | CoffeeScript | Free | Yes | Yes | 7.7 | |
| 14 | Opal | Yes | Free | Yes | 7.6 | |
| 15 | Mitosis | Yes | Free | Yes | 7.5 |
Head-to-Head
- Kotlin/JS vs Babel
- Kotlin/JS vs SWC
- Kotlin/JS vs Cython
- Kotlin/JS vs TeaVM
- Kotlin/JS vs Google Web Toolkit
- Kotlin/JS vs ClojureScript
Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
Last updated · How we research and update