When I load tested async HTTP clients at the BBC (for 1000rps), both https://hc.apache.org/httpcomponents-asyncclient-dev/ https://hc.apache.org/httpcomponents-

When I load tested async HTTP clients at the BBC (for 1000rps), both https://hc.apache.org/httpcomponents-asyncclient-dev/ https://hc.apache.org/httpcomponents-asyncclient-dev/ and https://github.com/AsyncHttpClient/async-http-client/ https://github.com/AsyncHttpClient/async-http-client/ performed well. We used Apache's since it exposes connection pool statistics. Apache's client doesn't have CompletableFuture, but it was easy to add one: https://gist.github.com/tomfitzhenry/4bb032f6a9f56d95f6fb54454e617fc1 https://gist.github.com/tomfitzhenry/4bb032f6a9f56d95f6fb544... async-http-client is the HTTP client used by Gatling (same developer, in fact).