In this article I'll show you a few ASP.NET HTML editors that you can use in your applications. For those who didn't know, HTML editors let you create rich text that can be stored in the database and rendered on pages. The output is formatted as HTML and that makes rendering extremely easy. Most of them have interface similar to writing applications such as Microsoft Word. HTML editors are often used in web application, especially in CMS systems.
FreeTextBox
So, let's start. My favorite HTML editor is FreeTextBox (FTB). It has all common features that we used to see in writing applications. Also, it has plenty of features such as Image Gallery, Office 2003/XP/2000/Mac buttons and JavaScript API that let's you add additional functionality. It is extremely easy to use. You'll have to add a reference to a dll, and create FTB tag on your page.
Image below shows FTB interface in full mode. You can try live demos here.
FreeTextBox Pro version has some extra features like Server-side XHTML conversion, color pickers and richer table manipulation. If you need some of those, you'll have to pay $49,99 for Pro licence.
TinyMCE
Next great editor is TinyMCE. Unlike FTB, it is JavaScript based WYSIWYG Open Source editor, that converts HTML Area element into a rich editor. It has similar functionality to FTB, which you can check here. It is well documented with instructions, examples, tips&tricks and other tutorials. Be sure to read the documentation if you are going to go for it.
The image below is a preview of TinyMCE with all features enabled.
There are two TinyMCE plugins that you can purchase: MCFileManager - file management utility and MCImageManager - An image gallery.
Winthusiasm HTML Editor for ASP.NET Ajax
The last one is the most interesting editor. Winthusiasm HTML Editor for ASP.NET Ajax (as you can guess) is specially designed for ASP.NET Ajax. It has basic functionality, but the most important thing is that it comes with full souce code in C# and JavaScript. That allows you to extend the editor to match your needs.
Another great thing is that you can read the article on Creating editor for ASP.NET Ajax that explains the implementation in details.
Image below shows demo that you can find on Winthusiasm website.
Complete code is available for download here.
Summary
There are more editors that have more or less same functionality, but those three stand out from the rest due to their simplicity, extensibility and implemented features. If you have problems or questions regarding installation and usage, just ask!