I've come across an interesting and robust membership management system for static websites called MemberSpace.com. Unfortunately I'm not thrilled with its content gating options: Is MemberSpace secure?
Their case studies are also impressive.
Are there any other similar solutions that are perhaps server based for content that run on top of your own web server while still allowing static content upload and gating? Are there any other competitors to this service in this space?
Open source or commercial options are both welcome.