CKEditor is the more common of the two in our index: it runs on 84 websites against 19 for Froala Editor. Counts come from real scans, not vendor claims.
CKEditor is a WYSIWYG rich text editor which enables writing content directly inside of web pages or online applications. Its core code is written in JavaScript and it is developed by CKSource. CKEditor is available under open-source and commercial licenses.
Froala Editor is a WYSIWYG HTML Editor written in Javascript that enables rich text editing capabilities for applications.
Want to know which one a particular site uses? Look it up and see its whole stack, or compare two sites side by side.