To address the need for interventions targeting social emotional development and mental health of young children in South Africa, the "Mazi Umntanakho" ('know your child') digital tool was co-designed, and piloted with caregivers and 3-5-year-old children involved in home visiting programmes promoting early childhood development. The aim of this study was to qualitatively evaluate the feasibility and acceptability of this tool in four urban and four rural low-income communities, from the perspective of home visitors and caregivers. Focus groups were conducted with home visitors (n = 117) and caregivers (n = 72). Issues relating to the feasibility of implementing the tool included timing of using the tool, technical and social implementation challenges, WhatsApp as the preferred platform, and participants' recommendations for future implementation. Overall, the tool was acceptable for home visitors and caregivers and was perceived to have a positive impact on children's development, and the relationship between caregivers and children.