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Head-to-head · Code Transpilers

Kotlin/JS vs Google Web Toolkit

  • Updated Oct 2026
  • Both researched from official sources
  • 5 checks side by side
Higher score Kotlin/JS #3 in Code Transpilers 8.8/10 Free plan Free plan✓ 3 of 4 features Visit Kotlin/JS
Google Web Toolkit #6 in Code Transpilers 8.5/10 Free plan Free plan✓ 2 of 4 features Visit GWT

Kotlin/JS leads on 0 checks, Google Web Toolkit on 0, and 5 are even. Who comes out ahead on the 5 yes/no, price and count checks where we have data for both products. The editor score weighs everything else too.

Our verdict

  • Highest scoreKotlin/JS · 8.8/10
  • Free planboth
  • Most featuresKotlin/JS · 3 of 4

Kotlin/JS scores higher on our rubric for code transpilers: 8.8 against 8.5 out of 10; our editors rank them #3 and #6.

Kotlin/JS is the better fit for kotlin teams targeting browsers or Node.js. Google Web Toolkit is the better fit for java teams building browser applications.

  • Kotlin/JS fits best

    Kotlin teams targeting browsers or Node.js

  • Google Web Toolkit fits best

    Java teams building browser applications

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Side by side

Feature Kotlin/JS 8.8/10 Visit ↗ Google Web Toolkit 8.5/10 Visit ↗
At a glance
Editor score 8.8 8.5
Ranking #3 in Code Transpilers #6 in Code Transpilers
Best for Kotlin teams targeting browsers or Node.js Java teams building browser applications
Pricing model Free Free
Starting price Free plan Free plan
Free plan ✓ ✓
Free trial — —
Deployment Self-hosted Self-hosted
Platforms Web, Windows, macOS, Linux Web, Windows, macOS, Linux
Support Community, Docs Community, Docs
Built for Solo, Small business, Mid-market, Enterprise Solo, Small business, Mid-market, Enterprise
Features Kotlin/JS 3/4 · Google Web Toolkit 2/4
Syntax-version conversion ✓ (best) Not checked yet
Intermediate output ✓ (best) Not checked yet
CLI access ✓ ✓
API access Not checked yet ✓ (best)
Specs
Source languages Not checked yet Not checked yet
Target languages Not checked yet Not checked yet
Conversion mode Source-to-source Source-to-source
Our review
Pros
  • Compiles to ES5 and ES2015 for browser and Node.js targets
  • Supports npm packages, webpack, and JavaScript module interoperability
  • Generates TypeScript declarations and offers production minification
  • Compiles client-side Java into optimized JavaScript
  • Includes Java APIs, UI widgets and JsInterop
  • Offers code splitting, debugging modes and JUnit testing
Cons
  • Requires Kotlin code and compatible dependencies as input
  • Projects are configured through the Kotlin Multiplatform Gradle plugin
  • Support channels are community resources and documentation
  • Requires Java development for client-side application code
  • Uses a self-hosted SDK rather than a hosted service
  • Support is centered on community resources and documentation
Our verdict

Kotlin/JS is a source-to-source compiler and development toolchain for building browser and Node.js applications with Kotlin. It transpiles Kotlin code, the standard library, and compatible dependencies into JavaScript, with ES5 and ES2015…

Read the review →

Google Web Toolkit is an open-source toolkit for building browser-based applications with client-side Java. Teams write application code in Java and compile it into JavaScript for web browsers. Its intended audience is Java teams that want…

Read the review →
  1. Kotlin/JSCode Transpilers 8.8Free plan
  2. Google Web ToolkitCode Transpilers 8.5Free plan

Strengths and trade-offs

  • Kotlin/JS — where it wins

    • Compiles to ES5 and ES2015 for browser and Node.js targets
    • Supports npm packages, webpack, and JavaScript module interoperability
    • Generates TypeScript declarations and offers production minification

    Where it doesn't

    • Requires Kotlin code and compatible dependencies as input
    • Projects are configured through the Kotlin Multiplatform Gradle plugin
    • Support channels are community resources and documentation

  • Google Web Toolkit — where it wins

    • Compiles client-side Java into optimized JavaScript
    • Includes Java APIs, UI widgets and JsInterop
    • Offers code splitting, debugging modes and JUnit testing

    Where it doesn't

    • Requires Java development for client-side application code
    • Uses a self-hosted SDK rather than a hosted service
    • Support is centered on community resources and documentation
  • Kotlin/JS8.8/10 · Free plan

    A free Kotlin-to-JavaScript toolchain for browser and Node.js projects.

    Visit Kotlin/JSFull verdict →
  • Google Web Toolkit8.5/10 · Free plan

    A Java-based route to browser applications, with compilation, widgets and testing tools.

    Visit GWTFull verdict →

More comparisons

All code transpilers comparisons → · Full ranking →

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Last updated · How we research and update