# h2o/h2o

H2O - the optimized HTTP/1, HTTP/2, HTTP/3 server

Repository: https://github.com/h2o/h2o
Canonical: https://ross.abutalabs.com/products/h2o
Homepage: https://h2o.examp1e.net
Language: C
License: MIT
License Family: permissive
Last push: 2026-08-04T04:56:33+00:00

## Health v2 (maintenance only)
Score: 75/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 96, release rhythm 34, longevity 100
- inputs: {"age_days": 4400, "days_push": 29, "days_rel": 226, "gap_med": null, "n_releases_24m": 1}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 11539, forks 883 (observed 2026-08-28T04:10:48.514157+00:00)

## What it is
H2O is an optimized HTTP server written in C supporting HTTP/1.x, HTTP/2, and HTTP/3 (QUIC), with features like server push, 103 Early Hints, ACME certificate automation, and FastCGI/reverse proxying. It can also be embedded as a library (libh2o) and scripted with mruby.

## Use cases
- serve static files over http2 and http3
- high performance web server with low latency
- reverse proxy with http3 support
- automate tls certificates with acme
- embed an http server in a c application
- scriptable web server with mruby rack apps

## When to choose
- you need top-tier HTTP/2 or HTTP/3 performance with low CPU and memory usage
- you want modern protocol features like server push, Early Hints, and extensible priorities
- you need a lightweight C-based server or embeddable HTTP library

## When to avoid
- you need a large ecosystem of third-party modules like nginx or Apache offer
- you prefer configuration without building from source, since versioned releases have ceased
- you need dynamic application hosting beyond FastCGI or mruby Rack

## Facets
- artifact type: application
- maturity: active
- function: http-server, web-framework, proxy, security
- domain: web-development, backend, performance, networking
- platform: cross-platform, cli
- tags: http2, http3, quic, tls, fastcgi, reverse-proxy, mruby, libh2o, high-performance, linux, macos, web-server

## Member repositories
- h2o/h2o (main) score 75

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:10:48.514157+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 2026-08-29T17:15:31.643950+00:00, confidence not recorded.
  - readme: https://github.com/h2o/h2o (fetched 2026-08-28T04:10:48.514157+00:00, sha e8dbebe9fb9c)
  - homepage: https://h2o.examp1e.net (fetched 2026-08-29T08:14:01.945087+00:00, sha 568942aae71c)
  - site_page: https://h2o.examp1e.net/install.html (fetched 2026-08-29T08:14:01.954760+00:00, sha df560f4b6741)
  - site_page: https://h2o.examp1e.net/faq.html (fetched 2026-08-29T08:14:01.957155+00:00, sha 4899fe339d91)
- Data as of 2026-08-30T08:39:29.467469+00:00.