Apollo vs Horizon: What are the differences?
Developers describe Apollo as "GraphQL server for Express, Connect, Hapi, Koa and more". Build a universal GraphQL API on top of your existing REST APIs, so you can ship new application features fast without waiting on backend changes. On the other hand, Horizon is detailed as "*A realtime, open-source JavaScript back end from RethinkDB *". Horizon provides a complete backend that makes it dramatically simpler to build, deploy, manage, and scale engaging JavaScript web and mobile apps. Horizon is extensible, integrates with the Node.js stack, and allows building modern, arbitrarily complex applications.
Apollo belongs to "Platform as a Service" category of the tech stack, while Horizon can be primarily classified under "Realtime Backend / API".
Apollo and Horizon are both open source tools. Apollo with 7.53K GitHub stars and 935 forks on GitHub appears to be more popular than Horizon with 6.77K GitHub stars and 389 GitHub forks.