Polyaxon core engine is open-source, has a Json API, webhooks, and an abstraction for creating components, and can be integrated with just about any other app or service.
Polyaxon provides an interface for authoring reusable components, there's a growing ecosystem of components that can be used by other Polyaxon users, but it's a big world out there. There are always useful integrations that don't yet exist, but should. Users can contribute new components to the public components registry or create private components for their own internal use.
Polyaxon also supports custom API integrations which can be authenticated with individual keys, and deliver outgoing webhooks based on particular events.