Sanity

Sanity starts with Sanity Studio, a web-based editor built for teams. It's real-time collaborative, so multiple people can edit the same content without stepping on each other. The Studio is customizable, letting you shape the UI to fit your content model.

Content is delivered as JSON over API, so your frontend is completely independent. It's a good fit for teams that want a sophisticated editing experience but also need to publish to multiple channels.