Azure AD B2C
Azure AD B2C Custom Policy Calling a REST API to get Additional Claims
This article shows you how you can create custom policies for Azure AD B2C that call a REST API to get additional claims to include in tokens.
Azure Functions
Using Azure Functions to Build a REST API with Custom Application Permissions
This article shows you how you can use Azure Functions to create a REST API with custom permissions that you grant to client applications calling your API.