The Undertow HTTP client was designed to be used in the reverse proxy, not so much as a general purpose HTTP client. The only real example of how to use it is at io.undertow.server.handlers.proxy.ProxyHandler, where it is used in the reverse proxy. It supports HTTP, AJP, SPDY and the current draft of HTTP2. It is 100% non-blocking and not thread safe, for the most part interaction with the client should be done in the IO thread of the connection. There has been some talk about adding a blocking/thread safe wrapper at some stage. The basic way that it is used is: - Connect to the remote host - Create a ClientRequest object and populate it with headers etc - Call ClientConnection.sendRequest with your request and a callback. When the connection is ready to send your request the callback will be invoked - If you want a request body use ClientExchange.getRequestChannel() to get a channel to use for sending - ClientExchange.setResponseListener() is used to register a listener to be notified of a response (you can also set handlers for HTTP 101 continue and server push events) - Once the response listener has been invoked you can get the client response from the exchange Stuart ----- Original Message -----