Cosmic JS provides a web dashboard to model and create content plus API Tools and Resources to integrate content with any website or app.
WordPress - WordPress is web software you can use to create a beautiful website or blog. We like to say that WordPress is both free and priceless at the same time.
Contentful - You don't need another CMS. You need a better way to manage content — unified, structured, and ready to deploy to any digital channel.
Craft CMS - Content management system built on Yii PHP Framework
Prismic - prismic.io is a web software you can use to manage content in any kind of website or app. API-driven.
HubSpot Website Platform - HubSpot Website Platform is a content management system that enables marketers to build websites personalized for every visitor.
GraphCMS - The GraphQL Headless CMS