This is libcurl. Only the include & the lib folders are taken from the distribution. See http://curl.haxx.se/libcurl/ for more info. We need a valid lib/config.h to build the static library. On the UNIX platforms the lib/config.h can be generated by using the following configure statement: ./configure --enable-http --enable-ftp --enable-file --enable-proxy --disable-pthreads --enable-nonblocking --enable-verbose --disable-ares --disable-manual --disable-ldap --disable-ldaps --disable-sspi --enable-crypto-auth --enable-cookies --without-libssh2 --without-nss --without-libidn --without-ca-path --without-gnutls On Windows-x86 the file lib/config-win32.h has been used as an initial template. Place this file, Makefile.kmk & the config files in the form config.h.TARGET.TARGET_ARCH in this directory after an update. 2019/03/18: Updated to cURL 7.64.0. Downloaded from https://curl.haxx.se/download/ 2018/11/30: Updated to cURL 7.62.0. 2017/12/14: Updated to cURL 7.57.0. Applied the diff against the previous version and fixed. The config.h.* files were manually updated but not regenerated. Tested by setting Version.kmk to an old version and running an update check in the GUI. 2015/05/04: Updated to cURL 7.42.1.