Html敏捷包是你的朋友。它经过很好的测试（应对标签汤以及格式良好的（X）HTML）。我也听说人们在生产应用中没有使用任何问题。

Does anybody know of a freely available .NET HTML DOM Parser?

The Html Agility Pack is your friend. It's been very well tested (coping with tag soup as well as well-formed (X)HTML). I've also heard that people have had not had any issues using it in production applications.