The main difference is that this enables private messaging between users, regardless if they are signed up or not. Next time you're in a thread, you'll see a button to send a message next to their username. Click, and it will start a message without you having to leave the page. HNChat on the other hand seems to be more of a separate place to have conversations as a group. I feel like there is a place for both, they just solve different problems

Very cool! I hadn't heard of HNChat but the authentication process is very similar. I like the idea of letting user's manually add the id if they want to. I think we may make it optional to automatically handle it for you or let you do it manually.

Biggest difference from my first impression of hnchat is that we built ours as a chrome extension and you participate directly on HackerNews instead of an external domain.