TinyMCE is an editor for web applications, you can integrate it into ASP.NET MVC easily. This is a platform independent web based Javascript HTML WYSIWYG editor control released as Open Source under LGPL by Ephox Corp.

TinyMCE has the ability to convert HTML TEXTAREA fields or other HTML elements to editor instances. Allows you to easily integrate into other Content Management Systems.

You can install from the npm, simply copy/paste this command into your terminal

$ npm install tinymce

or Bower

$ bower install tinymce-dist

or download it directly from https://www.nuget.org/packages/TinyMCE/

You can also install by copying & pasting the snippet below into your HTML page

<!DOCTYPE html>
<html>
<head>
  <script src="https://cloud.tinymce.com/stable/tinymce.min.js"></script>
  <script>tinymce.init({ selector:'textarea' });</script>
</head>
<body>
  <textarea>C# code || c sharp code !</textarea>
</body>
</html>

For more details about features and plugins you can visit https://www.tiny.cloud/