Hi @Harvey Mercado,
The API is not meant to be used for Single Sign-On; rather it's more of a tool for pushing and pulling data to/from Crowdstack programmatically.
Crowdstack uses SAML 2.0 for SSO, so in order to hook up your Crowdstack via SSO, you will need to implement a SAML Identity Provider on your registration and login system. In SSO mode, Crowdstack will act as a SAML Service Provider.
SAML 2.0 is an open standard with tons of information widely available. You can learn more about SAML 2.0 here:
You can also probably find a SAML SDK to ease your implementation. For example, OpenSAML is a C++ and Java SDK.
Note that Crowdstack uses SAML's HTTP POST binding, so you'll want to make sure you support that in your implementation.
Once you have your SAML Identity Provider in place on your website, you can share the SAML metadata XML to start the SSO configuration process in your Crowdstack control panel under Settings -> Single Sign-On.
The SAML metadata for your Crowdstack Service Provider can be found at the /saml/metadata path, relative to your Crowdstack domain.
Let us know if you have any questions about this!
Regards,
Brian