When comparing Netlify CMS vs Squidex, the Slant community recommends Netlify CMS for most people. In the question“What are the best open source headless CMS's?” Netlify CMS is ranked 6th while Squidex is ranked 17th. The most important reason people chose Netlify CMS is:
Experimental support for GitHub's GraphQL API is now available for the GitHub backend. Without mutation.
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Pros
Pro Experimental support for GitHub's GraphQL API
Experimental support for GitHub's GraphQL API is now available for the GitHub backend. Without mutation.
Pro Easy Creating Custom Widgets option
The NetlifyCMS exposes a window.CMS global object that you can use to register custom widgets, previews, and editor plugins. The same object is also the default export if you import Netify CMS as an npm module. The available widget extension methods are listed here.

Pro Modern

Pro Open-source

Pro Built in React.js
Pro Open source
Pro Versioning
Pro Powerful rule engine for integrations
Pro REST and GraphQL
Pro Slick UI
Pro Generous free package
2 locales, 2 collaborators, many API calls
Cons
Con A lot of configuration
Example: a few plugins and some code are needed for gatsby-img or markdown to work.
Con Limited to SImple Content
Limited to simple displaying of contents but will struggle with complex business rules ie ones that require cascading drop-downs, complex nested documents, etc..
Con Un-debuggable Script Editors
You can't debug any of its in-built script editors
Con References
It will allow you to delete references which are used by documents and when you come to open those documents, it will then perform its 'shake' logic to remove it (make it balnk') and will also disappear from history / versioning
Con UI can be messy to navigate for an editor
Con Small team
