# plasma-umass/doppio

Breaks the browser language barrier (includes a plugin-free JVM).

Repository: https://github.com/plasma-umass/doppio
Canonical: https://ross.abutalabs.com/products/doppio
Homepage: http://plasma-umass.github.io/doppio-demo
Language: TypeScript
License: MIT
License Family: permissive
Last push: 2022-12-06T23:14:10+00:00

## Health v2 (maintenance only)
Score: 23/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 5315, "days_push": 1366, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2183, forks 176 (observed 2026-08-28T04:06:23.522741+00:00)

## What it is
Doppio is a POSIX-compatible runtime system and a Java Virtual Machine (JVM) implemented entirely in TypeScript, allowing Java bytecode to run in the browser or on Node.js without any plugins. It was a PLDI 2014 research project from the PLASMA group at UMass Amherst.

## Use cases
- run java code in the browser without plugins
- execute java bytecode on node.js
- embed a jvm in a web application
- run java programs client-side with no install
- teach jvm internals with a readable typescript implementation

## When to choose
- you need to run untrusted or simple Java programs in a browser sandbox without installing Java
- you want a hackable, readable JVM implementation for research or teaching
- you want to execute Java bytecode on Node.js without a native JVM

## When to avoid
- you need a production-grade, high-performance JVM with full modern Java support
- you rely on the latest Java class libraries, JIT performance, or recent JVM features
- you need an actively maintained project - development has largely stalled

## Facets
- artifact type: library
- maturity: maintenance
- function: interpreter, compiler, developer-tools
- domain: programming-languages, compilers, web-development, developer-tools
- platform: browser, cross-platform
- tags: jvm, java, typescript, browser-runtime, virtual-machine, research-project, nodejs

## Member repositories
- plasma-umass/doppio (main) score 23

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:23.522741+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-30T02:48:15.369634+00:00, confidence not recorded.
  - readme: https://github.com/plasma-umass/doppio (fetched 2026-08-28T04:06:23.522741+00:00, sha 376786796d27)
  - homepage: http://plasma-umass.github.io/doppio-demo (fetched 2026-08-29T10:28:37.763708+00:00, sha 06be131ff5db)
- Data as of 2026-08-30T08:39:29.467469+00:00.