The site lives on GitHub Pages and does one specific thing well: pick a month and an activity, and it narrows the 63 US national parks to the ones that are actually pleasant to visit then. Each park card surfaces sample itineraries, fun facts, and travel hacks aggregated from Reddit threads — the layer of “what people who’ve been there actually say” that the NPS site is structurally never going to provide. Free, no account, no app.