We'd like to start using OAuth2 for SSO for a family of web apps. One solution is to use OAuth2 provided by Azure. It just looks unreasonably expensive, and I'm thinking there must be something I've missed.
As I understand it from Microsoft identity platform (v2.0) overview - Azure, any users that need to login with Azure's OAuth2 solution need to be in Active Directory. We don't need the users to be able to do anything else but log in to our apps, but we do want them to be our accounts and not any other accounts they may have with Microsoft already.
Looking at the AD price list, we're talking $6 user/month, if we want "Company branding (customization of logon & logout pages, access panel)" and SLAs which we do.
So assuming we have say 100,000 users that is $600,000 pr month just for OAuth2 so they can log in? Even if we could go through a "Diamond-gold-platinum partner" or something and could get that at a 1/10 of the price, it is still outrageous.
Other alternatives we're considering are Auth0, Okta or hosting our own Keycloak instance(s), so there are (much) cheaper alternatives, but is this the cheapest way to use OAuth2 for app logins with Azure's hosted OAuth2?
And will this interfere with other identities they also have with Microsoft, e.g. any Office365 accounts that have nothing to do with our applications?