# boazsegev/facil.io

Your high performance web application C framework

Repository: https://github.com/boazsegev/facil.io
Canonical: https://ross.abutalabs.com/products/facilio
Homepage: http://facil.io
Language: C
License: MIT
License Family: permissive
Topics: websocket-server, http-protocol, http-parser, c, concurrency, framework, webserver, networking, websockets, pubsub, redis-client, json, server-sent-events
Last push: 2026-04-14T06:37:17+00:00

## Health v2 (maintenance only)
Score: 57/100 (v2, computed 2026-09-02T17:46:02.011165+00:00)
- activity 77, release rhythm 8, longevity 100
- inputs: {"age_days": 3881, "days_push": 141, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: none
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 2400, forks 151 (observed 2026-08-28T04:06:43.774127+00:00)

## What it is
facil.io is a high-performance C micro-framework for web applications, providing an evented HTTP/1.1, WebSocket, and SSE server with pub/sub, optional Redis clustering, JSON parsing, Mustache templating, and TLS 1.3 support. Its 0.8.x line is being reorganized as fio-stl, a single-header C STL with an IO reactor, parsers, and cryptographic toolkit usable from C or C++.

## Use cases
- build a high performance http server in c
- write websocket applications in c
- handle 10k concurrent connections in c
- add pub/sub messaging with redis to a c app
- parse json in c without dependencies
- embed an evented network server in a c or c++ project
- power a ruby application server with http and websockets

## When to choose
- you need a fast, evented HTTP/WebSocket server in C or C++ with minimal dependencies
- you want built-in pub/sub, JSON, TLS 1.3, and crypto in one library
- you're building or serving a Ruby app via the Iodine server
- you need a single-header C STL with IO, parsers, and memory-safe utilities

## When to avoid
- you want a batteries-included web framework with routing, ORM, and middleware ecosystems
- your team is not comfortable developing in C
- you need Windows as a first-class production target (historically Linux/BSD/macOS focused)
- you prefer managed languages or runtimes over low-level systems programming

## Facets
- artifact type: framework
- maturity: active
- function: web-framework, http-server, websocket, serialization, json, caching, networking, cryptography, templating, cli
- domain: web-development, backend, networking, developer-tools
- platform: windows, bsd, cross-platform, c, cpp, ruby
- tags: evented-io, http1-1, server-sent-events, pub-sub, redis, c10k, single-header, tls-1-3, micro-framework, tcp-ip, real-time, linux, macos

## Member repositories
- boazsegev/facil.io (main) score 57

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:06:43.774127+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 2026-08-30T02:34:16.224783+00:00, confidence not recorded.
  - readme: https://github.com/boazsegev/facil.io (fetched 2026-08-28T04:06:43.774127+00:00, sha 260a84e8ae3e)
  - homepage: http://facil.io (fetched 2026-08-29T10:14:48.852085+00:00, sha e78d76257bdb)
  - site_page: https://facil.io/0.8.x (fetched 2026-08-29T10:14:48.862029+00:00, sha 3e27ee2d6d05)
  - site_page: https://facil.io/0.7.x (fetched 2026-08-29T10:14:48.864375+00:00, sha 17e185265eca)
  - site_page: https://facil.io/0.6.x (fetched 2026-08-29T10:14:48.866452+00:00, sha 14f6d1a56ddf)
  - site_page: https://facil.io/changelog (fetched 2026-08-29T10:14:48.868778+00:00, sha 6cee6ab14853)
- Data as of 2026-08-30T08:39:29.467469+00:00.