google/j2cl

Health v2 · maintenance only

Adoption not part of the score

1376 stars · 160 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

J2CL is a transpiler from Google that converts Java source code into Closure-style JavaScript, tightly integrated with Closure Compiler for optimization. It also supports compiling Java to WebAssembly and is the technology behind Google's GSuite apps like Gmail and Docs.

Use cases

• reuse existing Java libraries in a JavaScript web application
• compile Java code to JavaScript for the browser
• build web apps with Java on the frontend
• transpile Java to WebAssembly
• share business logic between Java backend and web frontend
• migrate a GWT application to modern tooling

When to choose

• you have substantial Java code or Java libraries (Guava, Dagger) you want to run in the browser
• you want strong static typing and cross-language type checks in frontend code
• you already use Bazel and Closure Compiler tooling
• you want to target WebAssembly from Java

When to avoid

• you are starting a greenfield frontend project with no Java investment
• you need full Java runtime semantics or reflection-heavy libraries
• you want a simple build without Bazel
• you need stable, finalized Wasm support

Facets

library · maturity active

compiler build-tool developer-tools compilers web-development programming-languages developer-tools jvm cross-platform transpiler java-to-javascript closure-compiler gwt wasm bazel jsinterop web-server

Member repositories

For agents

markdown · JSON · MCP: product_card(name="google/j2cl")