KANJIN (kanjin.app) is a free digital stamp card and back office for small walk-in shops. Customers join with their phone number or a QR poster and download nothing. The free plan has no time limit and no credit card: unlimited customers, 20 Google review requests and 5 AI review reply drafts a month, a daily ledger and 18 free tools. The paid plan is $39 a month or $390 a year per shop.