Can my employees sign in to my Catalyst app with their existing Zoho accounts while Public Signup is turned off?

No. In Catalyst CloudScale Authentication, social logins, including Zoho, are available only while Public Signup is enabled, and so is Custom User Validation. With Public Signup off, you add users yourself from User Management, and they sign in with the password they set for your app.

To let only named employees in with their Zoho accounts:

1. Enable Public Signup and the Zoho social login in CloudScale → Authentication.
2. Write a Basic I/O function that reads the sign-up request and returns status: "failure" for any email address that isn’t on your allow-list.
3. In Authentication → Whitelisting, turn on Custom User Validation, select the function and click Configure.
4. To remove someone’s access later, disable or delete them in User Management → Users, because Custom User Validation runs only when a user signs up, not at each sign-in.

Note: Catalyst doesn’t offer a sign-in limited to one company’s Zoho organization, and a Zoho sign-in creates a new app user rather than linking to a user you invited with the same email address.

Refer to the Custom User Validation help page for details.