Wagtail

vs

Nucleus CMS

Django CMS is a free and open-source content management system build on the Python web framework Django. With Django CMS, you can create your own website or blog in a matter of minutes which is easy to maintain far into the future. If you are a developer utilizing the Django framework you can integrate Django CMS into an exiting Django application and take advantage of it's publishing and editing features.

Strapi is a free and open source headless CMS developed with JavaScript for Node.js. The software makes it really simple to generate REST and GraphQL APIs. Simply create your database schema and relationships in the Strapi admin panel UI, and Strapi will auto-generate API endpoints to represent the data structures provided. Strapi comes packed with features you come to expect from normal CMS's such as authentication, authorization, content management and a media library. The software can be used for free and can be self-hosted on any server and platform. Extra enterpise functionallity is currently being developed, and will be sold at cost.

An open-source tool for managing content across all your omni-channel digital experiences. Directus is free and open-source headless CMS written in PHP, that takes a data first approach. Developers and content creators use Directus to manage content and generate a powerful API that can be used by any frontend technology. Directus can be self-hosted and is absolutely free.

ButterCMS is a commercial headless content management system and content API. With ButterCMS you can quickly setup your very own headless CMS that supports In-browser editing. Where you can quickly find and filter your images and files, update and schedule content and serve you assets over a content delivery network.

Quanta is a free, open source Content Management Framework thought for programmers and used for the creation of new-generation websites and applications.

Exponent CMS is a notable free and open source content management system that contains its own independent modular software framework of enterprise level.