RANCID (Really Awesome New Cisco confIg Differ) monitors the configuration of routers and other network devices. It logs into each device listed in router.db, runs commands to collect the relevant information, filters out constantly changing output, and stores the history in a revision control system: CVS, Subversion or Git. Differences from the previous run are emailed to a mailing list. Supported devices include Cisco, Juniper, HP ProCurve and Allied Telesis equipment, with community-contributed modules for other makes. RANCID is delivered as source code and runs on your own server; it requires Expect.
RANCID is maintained by Shrubbery Networks and is open source under a BSD-style licence. There is no hosted service: the collected configurations and their history exist only on infrastructure you operate yourself. That matters because device configurations can be sensitive. A European organisation keeps full control over location and access, with no dependence on a cloud provider.