It's hardcoded in HTTPie. Unclear how to obtain the actual version. ``` bash $ http -v https://nghttp2.org/httpbin/get ``` ``` http GET /httpbin/get HTTP/1.1 Accept: */* Accept-Encoding: gzip, deflate Connection: keep-alive Host: nghttp2.org User-Agent: HTTPie/0.9.1 ``` ``` http HTTP/2 200 access-control-allow-credentials: true access-control-allow-origin: * content-length: 268 content-type: application/json date: Sat, 07 Feb 2015 17:02:52 GMT server: nghttpx nghttp2/0.7.4-DEV strict-transport-security: max-age=31536000 via: 1.1 nghttpx ```