In pediatric patients, pain remains the most common complaint after surgery. This French multicenter epidemiological study (AlgoDARPEF) aimed to evaluate the use of a smartphone application (App) to assess the duration and severity of pain experienced by children undergoing outpatient surgery. Children younger than 18 years scheduled for an elective outpatient procedure in one of the participating centers were eligible. Parents were invited to provide daily information for 10 days regarding their child's pain and comfort through a smartphone App using the Parents' Postoperative Pain Measure-Short-Form (PPPM-SF). Children older than 6 years could also provide self-assessments of pain using a numerical rating scale (NRS)-11. Data regarding pain medication, preoperative anxiety, postoperative nausea and vomiting, and parent satisfaction were also analyzed. Repeated-measures analyses of variances (ANOVAs) were used to compare the self-assessments and hetero-assessments of pain. Eleven centers participated in the study, and 1573 patients were recruited. Forty-nine percentage of parents (n = 772) actually used the App at least once. In all surgeries, the average pain rating on the PPPM-SF scale did not exceed 3/10 throughout the follow-up period, as well as for 4 main surgical specialties. Age, visceral surgery, and preoperative anxiety ≥ 4/10 were identified as independent risk factors for experiencing at least 1 episode of pain ≥4/10 during the first 48 postoperative hours. Although these findings indicated that postoperative pain management seems to be satisfactory in the families who used the App, some improvements in anxiety management are suggested. This study shows that inviting parents to use a smartphone App to assess and report the quality of postoperative management in pediatric patients provides useful information. A continuous report regarding pain and adverse events over a 10-day postoperative period by a self-reporting or parent's contribution is possible. Future studies should investigate the ability of live data collection using an App to ensure fast, efficient interactions between patients and physicians.