New York City's D37 Public Employee Union welcomes more than 10,000 attendees to each of their hosted events. In order to automate check-in processes and reduce the number of manual steps required to record data, we developed native Android and iPhone applications that eliminate the need for sign-up sheets and tally counters. Because attendees are granted entry based on membership status, door attendants also required the ability to view the standing of each individual before entry. After receiving a physical or digital barcode specific to their person, each attendee will present it to the event's gatekeeper. Using an iPhone or Android device, the host will then scan the code using the Medullus attendance application. Once scanned, user data will appear to the host, giving them the ability to accept or deny entry based on user status. Highlighted features include API connection to membership database, built-in scanner, customized messaging, offline capabilities