BackgroundData access through smartphone applications (apps) has reframed procedure and policy in healthcare, but its impact in trauma remains unclear. Citizen is a free app that provides real-time alerts curated from 911 dispatch data. Our primary objective was to determine whether app alerts occurred earlier than recorded times for trauma team activation and emergency department arrival. MethodsTrauma registry entries were extracted from a level one urban trauma center from January 1, 2018 to June 30, 2019 and compared with app metadata from the center catchment area. We matched entries to metadata according to description, date, time, and location then compared metadata timestamps to trauma team activation and emergency department arrival times. We computed percentage of time the app reported traumatic events earlier than trauma team activation or emergency department arrival along with exact binomial 95% confidence interval; median differences between times were presented along with interquartile ranges. ResultsOf 3,684 trauma registry entries, 209 (5.7%) matched app metadata. App alerts were earlier for 96.1% and 96.2% of trauma team activation and emergency department arrival times, respectively, with events reported median 36 (24–53, IQR) minutes earlier than trauma team activation and 32 (25–42, IQR) minutes earlier than emergency department arrival. Registry entries for younger males, motor vehicle-related injuries and penetrating traumas were more likely to match alerts (P < .0001). ConclusionApps like Citizen may provide earlier notification of traumatic events and therefore earlier mobilization of trauma service resources. Earlier notification may translate into improved patient outcomes. Additional studies into the benefit of apps for trauma care are warranted.