CKEditor is a front-end component that does not require any backend infrastructure to work. However, some of its optional features (like Real-time Collaboration or document converters) come with complete backend solutions for storing data. You can choose the cloud (SaaS) to save the costs and hassle of maintaining your own server, or on-premises solutions to have full control over your data.
Read the documentation to learn more about CKEditor Cloud Services.
All of the cloud-based features can be easily tested through the 30-day free trial.