ASP.NET Tiny Security
ASP.NET Tiny Security Providers is a free, open source, pack of tiny ASP.NET Membership, Role and Profile providers. The goal of this project is to provide custom implementation of ASP.NET providers against some tiny data storages (XML, JSON)
Native support and usage by all ASP.NET membership controls;
Supports all password formats: Clear, Encrypted and Hashed;
Have In Mind
Because of the tiny data storages, it is not recommended to use this providers with "heavy-duty" membership sites (a lot of roles, users and big number of members).
Tiny Membership Providers best fit for sites with small number of authenticated users and hosted on servers with no SQL access.
For further details check out the Documentation.