# Koa

Expressive middleware for node.js using ES2017 async functions

Repository: https://github.com/koajs/koa
Canonical: https://ross.abutalabs.com/products/koa
Homepage: https://koajs.com
Language: JavaScript
License: MIT
License Family: permissive
Topics: koa
Last push: 2026-08-26T03:22:12+00:00
Link (homepage): https://koajs.com

## Health v2 (maintenance only)
Score: 94/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 99, release rhythm 84, longevity 100
- inputs: {"age_days": 4792, "days_push": 7, "days_rel": 104, "gap_med": 14, "n_releases_24m": 16}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 35689, forks 3227 (observed 2026-08-28T04:12:00.898445+00:00)

## What it is
Koa is an expressive HTTP middleware framework for Node.js built by the Express team, using async functions for cascading middleware. It has a small core (~570 SLOC) with no bundled middleware, providing content negotiation, redirection, and other common HTTP server helpers.

## Use cases
- build web apis in node.js
- write http servers with async middleware
- create minimal node.js web applications
- replace express with a lighter framework
- handle content negotiation and redirection in node

## When to choose
- you need a batteries-included framework with routing and middleware built in
- you want a large ecosystem of prebuilt plugins out of the box

## When to avoid
- you need a full-stack framework with built-in routing, validation, and auth
- you are not using node.js
- you rely on koa v1 generator middleware

## Facets
- artifact type: framework
- maturity: stable
- function: web-framework, http-server, middleware, routing
- domain: web-development, backend, apis
- platform: -
- tags: async, expressive, minimal, http, javascript, nodejs, web-server

## Member repositories
- koajs/koa (main) score 94
- koajs/examples (examples) score 48

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:12:00.898445+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 2026-08-29T16:26:45.331179+00:00, confidence not recorded.
  - readme: https://github.com/koajs/koa (fetched 2026-08-28T04:12:00.898445+00:00, sha 63df3e12ceb3)
  - homepage: https://koajs.com (fetched 2026-08-29T07:48:35.127359+00:00, sha bbea983eefb1)
- Data as of 2026-08-30T08:39:29.467469+00:00.