MasterSet: a free web app for tracking Pokémon card master sets as a digital binder

I collect Pokémon cards and wanted an electronic way to keep track of my master sets. Spreadsheets and notes apps never quite worked for me, so I built my own. What it does: Every set is shown as a 9-pocket binder. Cards you own are in full color and missing ones are greyed out, so you can see your progress at a glance. Each variant and printing gets its own pocket, since that's what makes master sets tricky to track. Why I made it: I wanted something I could pull up anywhere, anytime. The main use case for me is card shows: I can walk around the tables knowing exactly which cards I still need and which ones I already have, instead of guessing or buying duplicates. Details: It's free to track your master sets, and you don't need an account to start checking off cards. Signing in with Google saves your progress across devices. It works in desktop and mobile browsers, and it's deployed on Vercel. Right now it covers English sets, with Japanese sets planned next. What I'd love feedback on: First impressions of the binder layout, how it feels on mobile, and anything confusing when you first land on the site. If you collect, I'd also love to hear what features would make you actually use it. MasterSet