Here are two websites that can add syntax highlighting for C#, Java, HTML, .NET languages (such as ASP.NET), T-SQL, JavaScript (JS), VBScript (VBS), and many others:
1. **Highlight.js**: [https://highlightjs.org/](https://highlightjs.org/)
This is a highly popular library for syntax highlighting. It supports a wide range of programming languages, including the ones you mentioned.
2. **Prism.js**: [https://prismjs.com/](https://prismjs.com/)
Prism.js is another lightweight and efficient syntax highlighter that supports numerous languages and offers customizable options for adding colors and styles to code snippets.
Both tools provide easy integration into websites or documents to enhance the readability of your code with color and formatting.