The Spire Vessels API is a REST API premium service that returns only the most recent information provided for each vessel. It joins the position reports and static voyage reports which are transmitted in separate AIS messages into a single record. This saves the client from having to join AIS messages and keep track of MMSI linked to each IMO number.
Vessels API can be filtered to only return data for a specific list of vessels by IMO or MMSI number as well as return only vessels updated since a point in time.
Vessels API is documented here https://developers.sense.spire.com/get-started#vesselsApi
Note the granularity of AIS tracks received using Vessels API depends on the frequency with which the Vessels API is called as well as the frequency of reception of AIS data for a vessel.