Convert Markdown to HTML in .NET

Markdown Sharp is what the site uses and is available on NuGet.

Another implementation that seems to be gaining ground is MarkdownDeep

This is a full implementation for both C# and JavaScript. The MarkdownHelper on Nuget is using MarkdownDeep now instead of MarkdownSharp.

I've used both and MarkdownDeep seems to be more fully functional and having the JavaScript version is great for quick client side setups.

Check out Markdown Sharp. It's the open source library that resulted from the development of Stack Overflow and is much more robust/actively developed than markdown.net.

TL;DR: now it's 2021 use markdig

I just came across this questions and the answers are all quite old. It appears that implementations based on commonmark are the suggested way to go now. Implementations for lots of languages (including C#) can be found here