OpenCMS

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abecms

Sitecore A/S has produced the Sitecore content management system since 1999.

MODX is a free, open source content management system and digital experience platform. The CMS gives you full control over your creative, editorial vision and the experience you deliver. MODX is written in the programming language PHP and supports both MySQL and Microsoft SQL Server databases. The CMS is openly developed and released under the GPL license, and allows contribution.

Joomla is a free and open-source content management system written in PHP. The CMS is built entirely by volunteers from all over the world and has a strong community that provide educational resources, and extensions. 

Netlify CMS is a static site generator that is based on client-side JavaScript with a reusable APIs and prebuilt Markup. Simply pull in Netlify CMS to /admin of you site and you have an SPA (Single Page Application) admin panel that can edit content stored in a Git repository. Serving applications like this, the JAMstack way, improves performance, lowers cost of scaling and provides for a better development experience.

Jekyll is a static site generator written in Ruby. With Jekyll, you can transform your plain text into static websites or blogs. No more database, and cumbersome updates and install, simply focus on your content. In Jekyll, permalinks categories, pages, posts, and custom layouts are factored into the design, so you can get started writing content, right away. For layouts and template, Jekyll uses the Liquid templating language which allow you to design and structure a site to your liking. In a nutshell Markdown, Liquid, HTML and CSS goes in, and out comes a static site ready for deployment.

With no knowledge of PHP required at all you can make any static web-page editable by your clients.