LOGIN REST api for Zoho CRM

LOGIN REST api for Zoho CRM

I'm developing a mobile app which is using Zoho CRM apis i.e fetching list of CRM users, records and insert record. Is there any Zoho CRM api for user login?

I've generated access token from web portal able to get response of insert/get records apis. Before accessing all these records, to validate users credentials(email id and password), which api should be used?

Note: I have checked generating access token api which inputs password which will be generated from web portal. Account password can't be used to generate access token. I cannot use this api for login unitl I get generated password from web portal.
https://accounts.zoho.com/apiauthtoken/nb/create?SCOPE=ZohoCRM/crmapi&EMAIL_ID=gg@g.in&PASSWORD=[Generated password and not accout password]&DISPLAY_NAME=test123

Thanks for the help.