HTTP/2 with curl HTTP/2 Spec http2 explained Build prerequisites nghttp2 OpenSSL, libressl, BoringSSL, GnuTLS, mbedTLS, wolfSSL or Schannel with a new enough version. nghttp2 libcurl uses this 3rd party library for the low level protocol handling parts. The reason for this is that HTTP/2 is much more complex at that layer than HTTP/1.1 (which we implement on our own) and that nghttp2 is an already
