POST format for a chained create
CiviCRM allows you to send api params in POST by encrypting the params in json. Here is an example on how you can build api params used in REST call

http://www.domain.org/sites/all/modules/civicrm/extern/rest.php?entity=Contact&amp;action=create&amp;api_key=userkey&amp;key=sitekey&amp;json={"contact_type":"Individual","first_name":"test","last_name":"test","api.Address.create":{"location_type_id":"Home","street_address":"123 somewhere st"}}


You can use api explorer to build your params.



Thanks

Pradeep