mxisd is a federated Matrix Identity Server following a cascading lookup model, using LDAP (optional) then other identity servers, including the central Matrix servers.
It is targeted to people/organisation that run their own Homeserver for a specific domain and want to publish 3PID mapping without having to rely on central servers.
Is is an implementation of the [Identity Service API](http://matrix.org/docs/spec/identity_service/unstable.html) which aims to provide an alternative to [sydent](https://github.com/matrix-org/sydent).
