deepstream.io is described as 'clusterable realtime server that handles persistent tcp and websocket connections. It offers data-sync, pub/sub and request/response. It's available for Linux, Mac and Windows and comes with clients in JS, Java and many others' and is an app in the Development category. There are more than 10 alternatives to deepstream.io for a variety of platforms, including Online / Web-based, Mac, Linux, Self-Hosted solutions and Windows. The best alternative is Firebase, which is free. Other great apps like deepstream.io are Meteor (Free, Open Source), Etebase (Free, Open Source), Supabase (Free, Open Source) and MongooseIM platform (Free, Open Source).
Etebase makes it easy to build end-to-end encrypted applications by taking care of the encryption and its related challenges. Think Firebase but encrypted in a way that only your users can access their data.
MongooseIM is aimed at large, complex enterprise level projects, where real-time communication is critical for business success. It provides high availability, ease of deployment, development and reliability in production.