# microsoft/napajs

Napa.js: a multi-threaded JavaScript runtime

Repository: https://github.com/microsoft/napajs
Canonical: https://ross.abutalabs.com/products/napajs
Language: C++
License: NOASSERTION
License Family: other
Topics: javascript, multithreading, nodejs, napajs, runtime, parallel, multi-core
Archived: true
Last push: 2022-08-29T14:03:08+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 3333, "days_push": 1465, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: archived, no_license
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 9174, forks 329 (observed 2026-08-28T04:10:28.720062+00:00)

## What it is
Napa.js is a multi-threaded JavaScript runtime built on V8 that executes JavaScript across multiple V8 isolates with APIs for object transport, sharing, and synchronization between threads. It is distributed as a Node.js module and can also be embedded in a host process without Node.js.

## Use cases
- run CPU-bound JavaScript tasks in parallel
- offload heavy computation from the Node.js event loop
- execute JavaScript across multiple V8 isolates
- share and synchronize objects between JavaScript threads
- embed a JavaScript runtime in a native host process

## When to choose
- your Node.js workload is bottlenecked by CPU-bound tasks
- you need multi-threaded JavaScript with object sharing and synchronization
- you want to embed a V8-based JS runtime without a Node.js dependency

## When to avoid
- your workload is I/O-bound and Node.js async suffices
- you need a runtime under active development - the project has seen little recent activity
- modern Node.js worker_threads meet your parallelism needs

## Facets
- artifact type: library
- maturity: maintenance
- function: concurrency, interpreter, developer-tools
- domain: developer-tools, performance, backend
- platform: cpp, cross-platform, windows
- tags: multithreading, v8, cpu-bound, parallel-computing, javascript-runtime, worker-threads, nodejs, linux, macos

## Member repositories
- microsoft/napajs (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:28.720062+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 2026-08-29T17:23:22.534135+00:00, confidence not recorded.
  - readme: https://github.com/microsoft/napajs (fetched 2026-08-28T04:10:28.720062+00:00, sha 43e9b365d2ec)
- Data as of 2026-08-30T08:39:29.467469+00:00.