AbstractObjectivesIn‐hospital cardiac arrests are common and associated with high mortality. Smartphone applications offer quick access to algorithms and timers but often lack real‐time guidance. This study assesses the impact of the Code Blue Leader application on the performance of providers leading cardiac arrest simulations.MethodsThis open‐label randomized controlled trial included Advanced Cardiac Life Support (ACLS)–trained medical doctors (MD) and registered nurses (RN). Participants were randomized to lead the same ACLS simulation with or without the app. The primary outcome, “performance score,” was assessed by a trained rater using a validated ACLS scoring system. Secondary outcomes included percentage of critical actions performed, number of incorrect actions, and chest compression fraction (percentage of time spent performing chest compressions). A sample size of 30 participants was calculated to detect a difference of 20% at the 0.05 alpha level with 90% power.ResultsFifteen MDs and 15 RNs underwent stratified randomization. The median (interquartile range) performance score in the app group was 95.3% (93.0%–100.0%) compared to 81.4% (60.5%–88.4%) in the control group, demonstrating an effect size ofr= 0.69 (Z= −3.78,r= 0.69,p= 0.0002). The percentage of critical actions performed in the app group was 100% (96.2%–100.0%) compared to 85.0% (74.1%–92.4%) in the control group. The number of incorrect actions performed in the app group was 1 (1) compared to 4 (3–5) in the control group. Chest compression fraction in the app group was 75.5% (73.0%–84.0%) compared to 75.0% (72.0%–85.0%) in the control group.ConclusionsThe Code Blue Leader smartphone app significantly improved the performance of ACLS‐trained providers in cardiac arrest simulations.