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Head-to-head · Code Transpilers

TeaVM vs Scala.js

  • Updated Oct 2026
  • Both researched from official sources
  • 4 checks side by side
Higher score TeaVM #5 in Code Transpilers 8.6/10 Free plan Free plan✓ 2 of 4 features Visit TeaVM
Scala.js #8 in Code Transpilers 8.3/10 Open source ✓ 3 of 4 features Visit Scala.js

TeaVM leads on 0 checks, Scala.js on 0, and 4 are even. Who comes out ahead on the 4 yes/no, price and count checks where we have data for both products. The editor score weighs everything else too.

Our verdict

  • Highest scoreTeaVM · 8.6/10
  • Free planonly TeaVM
  • Most featuresScala.js · 3 of 4

TeaVM scores higher on our rubric for code transpilers: 8.6 against 8.3 out of 10; our editors rank them #5 and #8.

On conversion mode, Scala.js gives you Both where TeaVM offers Source-to-source.

TeaVM is the better fit for java teams targeting JavaScript or WebAssembly. Scala.js is the better fit for scala teams building JavaScript applications.

  • TeaVM fits best

    Java teams targeting JavaScript or WebAssembly

  • Scala.js fits best

    Scala teams building JavaScript applications

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Side by side

Feature TeaVM 8.6/10 Visit ↗ Scala.js 8.3/10 Visit ↗
At a glance
Editor score 8.6 8.3
Ranking #5 in Code Transpilers #8 in Code Transpilers
Best for Java teams targeting JavaScript or WebAssembly Scala teams building JavaScript applications
Pricing model Free Free
Starting price Free plan Open source
Free plan ✓ (best) Not checked yet
Free trial — —
Deployment Self-hosted Self-hosted
Support Email, Docs Community, Docs
Integrations 7 integrations 5 integrations
Built for Small business, Mid-market, Enterprise Solo, Small business, Mid-market, Enterprise
Features TeaVM 2/4 · Scala.js 3/4
Syntax-version conversion Not checked yet Not checked yet
Intermediate output Not checked yet ✓ (best)
CLI access ✓ ✓
API access ✓ ✓
Specs
Source languages Not checked yet Not checked yet
Target languages Not checked yet Not checked yet
Conversion mode Source-to-source Both
Our review
Pros
  • Compiles Java bytecode to JavaScript and Java or Kotlin to WebAssembly GC
  • Maven and Gradle integration with JavaScript interoperability
  • Includes source maps, debugging, development servers, and browser testing
  • Incremental compilation supports iterative Scala-to-JavaScript builds
  • Dead-code elimination and linking help shape JavaScript output
  • Interop includes JavaScript libraries, React, AngularJS, Node.js, and Vite
Cons
  • Works within TeaVM’s supported Java API constraints
  • Focused on new web applications and selected code reuse, not every Java workload
  • Requires self-hosted deployment
  • Requires Scala source code, so it is not a general-purpose transpiler
  • Project workflows are commonly managed through build tools such as sbt
  • Support is through community channels and documentation
Our verdict

TeaVM is an open-source ahead-of-time compiler for Java, Kotlin, and Scala developers who want to build web front ends or reuse selected backend code in browser applications. It compiles Java bytecode to JavaScript, supports Java and…

Read the review →

Scala.js brings Scala into JavaScript application development by compiling Scala source files into JavaScript. It is aimed at teams that want to write application logic in Scala while targeting browsers, Node.js, or JavaScript modules. The…

Read the review →
  1. TeaVMCode Transpilers 8.6Free plan
  2. Scala.jsCode Transpilers 8.3Open source

Strengths and trade-offs

  • TeaVM — where it wins

    • Compiles Java bytecode to JavaScript and Java or Kotlin to WebAssembly GC
    • Maven and Gradle integration with JavaScript interoperability
    • Includes source maps, debugging, development servers, and browser testing

    Where it doesn't

    • Works within TeaVM’s supported Java API constraints
    • Focused on new web applications and selected code reuse, not every Java workload
    • Requires self-hosted deployment

  • Scala.js — where it wins

    • Incremental compilation supports iterative Scala-to-JavaScript builds
    • Dead-code elimination and linking help shape JavaScript output
    • Interop includes JavaScript libraries, React, AngularJS, Node.js, and Vite

    Where it doesn't

    • Requires Scala source code, so it is not a general-purpose transpiler
    • Project workflows are commonly managed through build tools such as sbt
    • Support is through community channels and documentation
  • TeaVM8.6/10 · Free plan

    A free, open-source compiler for Java teams building browser applications or native targets.

    Visit TeaVMFull verdict →
  • Scala.js8.3/10 · Open source

    An open-source Scala-to-JavaScript toolchain with incremental builds and JavaScript interoperability.

    Visit Scala.jsFull 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