Thanks for the feedback! I figured that short videos throughout the website would be enough to describe visually what Tandem is, but a short video at the top would probably be better.
And yeah, there are a ton of UI design tools out there on the web, it's been my #1 concern when building this thing out because they all promise similar tooling. Though, I'm trying to position this app as more of an Atom, or VSCode-like since it's geared to be another kind of extensible development environment. I figured that open sourcing it would be a first good step for that since developers would probably need to understand the internals before writing plugins for new UI tools, code writers, etc.
I went ahead and added a "Fork me on GitHub" badge to make it more clear that this is open source.
I like it in concept, but there's been an explosion of UI design tools recently and if you want to keep our attention, we need more of a demo. Perhaps the show HN would have been better postponed a bit.