CFFI bindings to WinHttp.dll. Provides a native HTTP client for those few Common Lisp Windows users.

1. Introduction

The canonical Common Lisp HTTP client is drakma which makes use of cl+ssl. This in turn requires openssl binaries installed on your system. All of this works great on Linux but on Windows this is generally a very poor experience.

However, Microsoft ships a fully featured HTTP client (WinHttp.dll) with Windows and is available on all Windows systems, no installing third party libraries is required.

This project provides a set of cffi bindings to the WinHttp API.


For almost all uses, the HTTP-REQUEST function is sufficient. It allows sending POST data, optional extra headers, basic authentication credentials.

(http-request "")

For advanced uses, make use of the with-http, with-connect, with-request macros and other functions. See the relevant MSDN pages for usage of the underlying APIs.


I've included an example XML-RPC client that I have found useful. It is largely taken from the S-XML-RPC project, replacing the http client with winhttp.

(xmlrpc:call "https://username:password@hostname:port/RPC2" "xmlrpc_method" arg1 arg2 ...)


Released under the terms of the MIT license.

Frank James July 2017.

Frank James <>