Stream Framework is a Python library, which allows you to build news feed, activity streams and notification systems using Cassandra and/or Redis. The authors of Stream-Framework also provide a cloud service for feed technology:
Web UI for decentralized social networks and marketplaces. Features: blogs, posts, comments, likes, reputation, feed and notifications. Built with Next.js, React and Ant Design.
NOTE: Development continues in https://github.com/dappforce/subsocial-parachain repo. Subsocial full node with Substrate/Polkadot pallets for decentralized communities: blogs, posts, comments, likes, reputation.