ButterCMS is a CMS and blog engine that slides into any new or existing website in minutes. Butter gives marketing teams the CMS they've always dreamed of without creating a hassle for developers.
Sanity is the platform for structured content. It comes with an open-source editing environment called Sanity Studio that you can customize with JavaScript and a real-time hosted data store.
Strapi is the leading open-source Headless CMS. It gives developers the freedom to use their favorite tools and frameworks while allowing editors to easily manage their content and distribute it anywhere. Based on Node.JS, it saves days of development time through a beautiful admin panel anyone can use. Strapi believes that everyone should have the power to create content, digital products, and user experiences that impact the world.