# undertow-io/undertow

High performance non-blocking webserver

Repository: https://github.com/undertow-io/undertow
Canonical: https://ross.abutalabs.com/products/undertow
Homepage: https://undertow.io
Language: Java
License: Apache-2.0
License Family: permissive
Topics: hacktoberfest, ajp, http, http-server, jakartaee, jakartaee10, java, java-nio, jboss, servlet, web, websocket, wildfly
Last push: 2026-08-14T19:06:33+00:00

## Health v2 (maintenance only)
Score: 93/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 97, release rhythm 84, longevity 100
- inputs: {"age_days": 5159, "days_push": 19, "days_rel": 105, "gap_med": 11.0, "n_releases_24m": 15}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3760, forks 1054 (observed 2026-08-28T04:08:17.871348+00:00)

## What it is
Undertow is a high-performance, non-blocking Java web server built on NIO, providing a core HTTP server, a Servlet 4.0/5.0/6.0 container, and WebSocket support. It is fully embeddable with a fluent builder API and a composition-based handler architecture, and serves as the default web server in WildFly.

## Use cases
- embed a lightweight http server in a java application
- run a servlet container without a full application server
- serve websockets from a java backend
- build a custom non-blocking http server from composable handlers
- replace tomcat or jetty with a faster embedded server
- support http/2 in a java service

## When to choose
- you need an embeddable, high-performance Java HTTP server with low overhead
- you want servlet support without a heavyweight application server
- you need WebSocket or HTTP/2 support on the JVM
- you want fine-grained control over server composition via handlers

## When to avoid
- you need a non-JVM stack
- you want a batteries-included full application server rather than a library
- your team is unfamiliar with NIO and non-blocking programming models

## Facets
- artifact type: library
- maturity: stable
- function: http-server, websocket, middleware, routing
- domain: web-development, backend, developer-tools
- platform: jvm, cross-platform
- tags: nio, servlet-container, http2, embeddable, wildfly, ajp

## Member repositories
- undertow-io/undertow (main) score 93

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:17.871348+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 2026-08-29T18:28:54.726996+00:00, confidence not recorded.
  - readme: https://github.com/undertow-io/undertow (fetched 2026-08-28T04:08:17.871348+00:00, sha 7d421d7ffb16)
  - homepage: https://undertow.io (fetched 2026-08-29T09:22:55.513944+00:00, sha bf265f0049a3)
  - site_page: https://undertow.io/documentation.html (fetched 2026-08-29T09:22:55.580109+00:00, sha 18b4c1fd1dcf)
- Data as of 2026-08-30T08:39:29.467469+00:00.