Build a rich text editor or build plugins for SummerNote. Backend language must be C#

Our project requires a rich text editor. We were thinking about CKeditor and Tinymce however they are charging monthly fees now and they are not cheap. The open course one we are looking for is "Summernote". The requirements are listed below: Requirement 1: Extend Summernote with a image library feature that the user can upload the image and it can be used in the future(saved on the server). To talk to the backend, you must use C# to develop it. We do not accept PHP. Requirement 2: When upload the image, the user will be able to crop the image. The user can define the size of the image by putting the width and length of it. Requirement 3: Create a button that the user can make the text italic. If you have played with Wordpress, we are very happy with what Wordpress rich text editor is offering. If you could develop something like Wordpress does, we are very happy to purchase it from you. Be aware that we only take C# code. If you have any other ideas other than summernote you can always point it out.