I am using approved client id with test_mode:false, in api, an opening the template in mobile app. the domain registered in client id is same from which i am sending the template .
Error--> Domain mismatch for client ---. This page can only be viewed from ---, unless the signature request is a test and "skipDomainVerification" is set to true in the HelloSign Embedded "open()" method. See the documentation for more info.
I'm hoping that since then your issue has been solved. A "Domain mismatch" error means that you are loading HelloSign iFrame outside of the approved domain for this specific app.
If you are going to load the iFrame on another domain that does not belong to your approved domain for testing purposes, add the test_mode parameter in the API backend call and "skipDomainVerification" is set to true in the HelloSign Embedded "open()" method. You will be able to load the iFrame on your local machine or any other domains.