# react/metro

🚇 The JavaScript bundler for React Native

Repository: https://github.com/react/metro
Canonical: https://ross.abutalabs.com/products/metro
Homepage: https://metrobundler.dev
Language: JavaScript
License: MIT
License Family: permissive
Topics: javascript, react-native, bundler
Last push: 2026-08-26T18:52:02+00:00

## Health v2 (maintenance only)
Score: 99/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 98, longevity 100
- inputs: {"age_days": 3549, "days_push": 7, "days_rel": 14, "gap_med": 11, "n_releases_24m": 32}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 5627, forks 692 (observed 2026-08-28T04:09:25.836113+00:00)

## What it is
Metro is the JavaScript bundler for React Native, providing fast bundling, a transformer pipeline, and a development server with hot reloading. It ships with React Native by default and can also be used standalone via its CLI or programmatic API.

## Use cases
- bundle javascript for react native apps
- run a dev server with fast refresh for react native
- build a production js bundle with source maps
- integrate a bundler middleware into an express server
- customize module resolution and transformation for react native
- serve bundles for thousands of modules in a large app

## When to choose
- you are building or tooling a React Native application
- you need fast incremental bundling and hot reload for mobile JS
- you want a programmable bundler with resolver/transformer/serializer hooks

## When to avoid
- you are bundling a plain web app where webpack, esbuild, or Vite fit better
- you need a general-purpose bundler outside the React Native ecosystem
- your project does not use Node.js-based tooling

## Facets
- artifact type: cli-tool
- maturity: active
- function: build-tool, http-server, middleware, cli, developer-tools
- domain: mobile-development, frontend, developer-tools, web-development
- platform: cli, cross-platform
- tags: bundler, react-native, javascript-bundler, module-bundler, hot-reload, dev-server, source-maps, transformer-pipeline, javascript, nodejs

## Member repositories
- react/metro (main) score 99

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:09:25.836113+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 2026-08-29T17:55:21.713459+00:00, confidence not recorded.
  - readme: https://github.com/react/metro (fetched 2026-08-28T04:09:25.836113+00:00, sha 07310f74e2d5)
  - homepage: https://metrobundler.dev (fetched 2026-08-29T08:50:19.165764+00:00, sha b4b82262f455)
  - site_page: https://metrobundler.dev/docs/getting-started (fetched 2026-08-29T08:50:19.168225+00:00, sha ee890284b776)
  - site_page: https://metrobundler.dev/docs/api (fetched 2026-08-29T08:50:19.170461+00:00, sha cfa994b7a934)
  - site_page: https://metrobundler.dev/docs/configuration (fetched 2026-08-29T08:50:19.172258+00:00, sha 114e72e6849b)
- Data as of 2026-08-30T08:39:29.467469+00:00.