# CELUM Connectors Here you'll find the configurable properties of our reusable [CELUM Connectors](https://www.brix.ch/extensions/celum-extensions). In contrast to the [extensions](/celum_extensions) that run inside CELUM, connectors run in some 3rd-party system and connect to CELUM from the outside via an API. So the two systems must be able to communicate between one another in order for this to work.