Currently, none of the HTTP2-specific APIs are available through Fastify, but Node’s and res can be accessed through our and Reply interface. PRs are welcome.

ALPN negotiation allows support for both HTTPS and HTTP/2 over the same socket. Node core and res objects can be either or HTTP/2. Fastify supports this out of the box:

Plain or insecure

If you are building microservices, you can connect to HTTP2 in plain text, however, this is not supported by browsers.