ComponentOne RichTextBox for UWP
RichTextBox for UWP Key Features

RichTextBox for UWP allows you to create customized, rich applications. Make the most of RichTextBox for UWP by taking advantage of the following key features:

The C1RichTextBox control supports displaying and editing rich text formatted as HTML. Load existing HTML content into the C1RichTextBox control, edit the document, and then save it back as HTML or plain text.

Select text and move the input caret easily by either mouse or touch input. The text selection is modeled after the native TextBox behavior so it's familiar and easy to accomplish on a touch device.

Edit and format text containing multiple fonts, decorations, sizes, colors, and other basic HTML style attributes supported by CSS and inline markup.

The C1RichTextBox control fully supports the clipboard for both plain and rich text through the keyboard (CTRL+C, CTRL+V, CTRL+X) and UI commands for touch displays. Implement cut/copy/paste commands within your AppBar or any other way imaginable.

The AppBar library includes built-in tools that you can use with the C1RichTextBox control to speed up command creation for common editing features like text formatting and document history. The built-in tools support the following commands: Bold, Italic, Underline, Undo, Redo, Increase Font Size, Decrease Font Size, Center Align, Right Align, Left Align, and Justify.

The C1RichTextBox control supports inserting and navigating hyperlinks. When the user clicks a hyperlink the RequestNavigate event is fired on the control and you can handle what happens from there.

The C1RichTextBox control supports inserting images from the Web or from the users machine. You can also insert tables. The Beta version has limited editing support for tables and images.

The C1RichTextBox control keeps track of all document history, so users have the ability to easily undo and redo changes. By default, keyboard commands (CTRL+Z/CTRL+Y) perform these actions.