As part of developing the Xiippy platform, we have been working on a superbly scalable and secure OIDC server for the platform that remains scalable and able to handle millions of user accounts without the typical cost structure of the likes of AWS Cognito and Microsoft Entra ID (aka Azure AD), which at high number of users, can become quite costly despite their entry-level free offerings for the first few thousands of users.
We have been impressed by OpenIDDict as a strong and active contender but the challenge with it is that despite its immense extendible design, still work had to be done to turn it into the monstrously scalable solution we intended, the first step of which was to offer a DynamoDB oriented storage and data persistence provider for it, which is now available at https://github.com/Xiippy/Xiippy.OpenIddict.AmazonDynamoDB.Stores on Github.
Packaged with additional security features like Argon2 password hashing and zero-data PII verification abilities, we will be releasing the identity solution as an independent solution in close future.