Owners (or users) are a critical part of any CRM system, allowing the ownership of any object to a relevant person (or perhaps a specified queue). We recommend that you store a mapping of HubSpot users to users within your system.
Poll the ‘Get List of Owners’ endpoint at regular intervals (as with all endpoints, no more often than once every five minutes) for any new or updated HubSpot users, and then update your internal database with the new user data, relating it back to an existing user or creating a new user where the returned ‘ownerId’ doesn’t match that of any existing user records. Users can also be representative of a lead queue, for example. Ideally, you'll keep a mapping of HubSpot owner ids to your applications user object identifier.
We recommend keeping a timestamp of the last update to any given HubSpot User within your internal system, and then comparing that with a timestamp taken whenever an update API call is made to HubSpot to ensure that your internal database always contains the latest user data.