pugixml - A light-weight C++ XML processing library.
Unimus - Unimus is a Network Automation and Configuration management (NCM) solution designed for fast deployment network-wide and ease of use. Unimus does not require learning any abstraction or templating languages, and does not require any coding skills.
Xerces-C++ - A C++ written processor for parsing, validating, serializing, and manipulating XML.
Oxidized - configuration backup software (IOS, JunOS) - silly attempt at rancid
GenieACS - A fast and lightweight TR-069 Auto Configuration Server (ACS)