The API is deployed across all Exoscale zones. When performing a compute call, you should use the relevant zone for your resource. For example: https://api-de-fra-1.exoscale.com/v2/instance would return only the instances from de-fra-1, https://api-ch-gva-2.exoscale.com/v2/instance from ch-gva-2. To obtain a list of all instances across all zones, you would need to do the corresponding request for each zone.