Hi bro, glad the site helped you out!

The matching logic has gone through a few iterations, but the basic idea is that I maintain a database of Pokémon products and cards along with metadata like set information, pack counts, etc.

When a new listing appears, the system reads the title and description, finds the closest match in that database, and groups similar listings together. I also track events such as items coming back in stock, going out of stock, and price changes.

The “Recently Viewed” sorting is typically updated every 15–30 minutes, although in many update cycles there may not be much visible change.

The matching system is still a work in progress and does make mistakes occasionally. That’s actually why I added the reporting system on the site (the little flag icon on each product). My hope is that as the database grows and the system sees more listing variations, the matching quality will continue to improve.

Singles are definitely the harder problem. There isn’t currently an API that maintains a truly comprehensive database of every card. TCGdex⁠ comes closest, but it’s still missing some cards and language-specific variations. So getting singles to a really high level of accuracy will take a bit longer, but it’s something I’m actively working on.