Add gateways and Devices using Integration of ThingsBoard

I’m looking for some guidance on Integration with ThingsBoard. Here We already used ThingsBoard as our cloud server and manage all data using MQTT.
We Integrate the as per link :ChirpStack Integration | ThingsBoard Cloud
Now we are able so see the data from node to Thingsboard devices.
In Chirpstack we add gateways and devices manually so my question is any API that all gateways and devices made from ThingsBoard. So please suggest that How we managed all functions without using Chirpstack web-page direct use of Thingsboard webpage. Any solution for This?

Please see: