Zoho Assist API uses appropriate HTTP verbs for every action.

GETUsed for retrieving resources.
POSTUsed for creating resources and performing resource actions.
PUTUsed for updating resources.
DELETEUsed for deleting resources.

Using GET method, you can retrieve data for a particular instance from the resource.

To get a list of customers,

$ curl --location --request GET 'https://assist.zoho.com/api/v2/user' \
--header 'Authorization: Zoho-oauthtoken {access_token}'