The best free alternative to TinyMCE is Trumbowyg, which is both free and Open Source. If that doesn't suit you, our users have ranked more than 25 alternatives to TinyMCE and many of them is free so hopefully you can find a suitable replacement. Other interesting free alternatives to TinyMCE are ContentTools (Free, Open Source), Editor.js (Free, Open Source), Aloha Editor (Free, Open Source) and CrossBrowdy (Free, Open Source).
ContentTools vs TinyMCE opinions
Most users think ContentTools is a great alternative to TinyMCE.
Integrated toolbar (includes color picking) in a textarea or div.
Editor.js is a block-styled editor for rich media stories. It outputs clean data in JSON instead of heavy HTML-markup. And more important thing is that Editor.js is designed to be API extendable and pluggable. So there are few key features: 1. Clean data output