Objectives: Parent management training is an effective treatment for disruptive behavior disorders but it is often underutilized in clinical settings. Access to care is limited due to logistical barriers as well as limited service availability. This study examines in an open trial the acceptability, feasibility, and clinical effects of a digital parent management training intervention that includes videoconference coaching, called "Tantrum Tool." Methods: Fifteen children, ages 3-9 years, participated in an open trial of an 8-week intervention. The primary symptom measure was the Disruptive Behavior Rating Scale (DBRS), and the secondary outcome measure was the Affective Reactivity Index (ARI) completed by the primary caregiver before and after treatment. Results: Treatment retention was high (80%), and parents reported a high level of satisfaction with the program. There was a significant reduction in the mean DBRS score from 13.5 ± 5.5 at baseline to 7.3 ± 3.4 at endpoint, p < 0.001. There was also a significant reduction in the mean ARI irritability score from 7.2 ± 2.6 at baseline to 3.75 ± 2.1 at endpoint, p < 0.01. Conclusions: This open pilot study supports the feasibility and acceptability of a digital parent training program for young children with disruptive behavior. Findings provide preliminary support for a clinically meaningful reduction of both disruptive behavior and irritability. Using the Tantrum Tool to deliver online treatment for children could increase access to first-line treatments for disruptive behavior and irritability in young children. ClinicalTrials.gov: NCT03697837.