H2O is a very fast HTTP server written in C. It can also be used as a library.
It supports:

- HTTP/1.0, HTTP/1.1
- [HTTP/2](http://http2.github.io/)
- draft 16 (and draft 14 to support older clients)
- persistent connections
- chunked encoding
- negotiation methods: NPN, ALPN, Upgrade, direct
- dependency and weight-based prioritization
- server push
- TLS
- uses [OpenSSL](https://www.openssl.org/)
- forward secrecy
- AEAD ciphers
- OCSP stapling (automatically enabled)
- session resumption (internal memory)
- conditional GET using last-modified / etag
- mime-type configuration
- reverse proxy
- persistent upstream connection

WWW: https://github.com/h2o/h2o