Letters uses the CKEditor Cloud Services as a backend to support collaborative editing, comments, discussions and the Easy Image uploads.
To support collaborative editing, the CKEditor Cloud Services stores customer document only temporarily in the server memory under a condition that at least one user is connected to the service editing that document. After the last user disconnects and a reasonably short period of time passes (typically around 15 minutes), the document is removed from the cloud and is stored in and by your application exclusively.
However, to support comments and discussions added to a document, they are permanently stored in the CKEditor Cloud Services with maximum data security through encrypted form, with different secret keys to encrypt the content used for each customer. The document itself contains only comment markers ("bookmarks"). For more details on storing comments refer to our documentation.
Images are also stored permanently in the CKEditor Cloud Services as they are handled by the Easy Image service to support responsive images via Content Delivery Network (CDN). For more details on Easy Image refer to the Easy Image overview and the Easy Image service details.