Discrete Trial Training (DTT) is one of the most effective training methods for children diagnosed with Autism. Traditional DTT suffers from limitations of inconsistencies on account of human error, disruptions due to in-session data collection by trainers, and difficulties of producing physical within-stimulus prompts. Current software solutions either support sole child usage thereby eliminating the social interaction benefits of DTT or lack automated data collection. Designed by an inter-disciplinary team of software engineers, HCI, and psychology experts and certified behaviour analysts for a touch-tabletop, DTTAce is an assistivesoftware that provides digital consistency and integrity and supports customization of trials, automated data collection, and within-stimulus prompts while preserving natural interactions and the social nature of DTT. It is an important step towards designing effective assistive software for Discrete Trial Training.