Generally speaking, in Open Source, the editor's source code and its modifications must remain accessible under the same Open Source license terms, and you must keep the copyright notices in each file intact and not delete the LICENSE.md file located in the CKEditor 4 and CKEditor 5 installation folders.
- CKEditor 5 is licensed under the terms of GPL 2+.
- CKEditor 4 is licensed under the terms of any of the following licenses at your choice: GPL, LGPL and MPL.
For more information on license requirements visit Open Source.
Please note that CKEditor 4 reached its End of Life (EOL) in June 2023. From then on, it receives no more updates, new features, bug fixes, and most importantly, security patches.
If you have an active CKEditor 4 subscription and need help, you can contact our support team. If you are not ready to migrate yet, for a limited time we are offering a paid Extended Support Model that will protect you against security vulnerabilities and/or breaking third-party API changes.