ObjectiveMany children in low-income and middle-income countries are disadvantaged in achieving early developmental potential in childhood as they lack the necessary support from their surroundings, including from parents and caregivers. Digital technologies, such as smartphone apps, coupled with iterative codesign to engage end-users in the technology-delivered content development stages, can help overcome gaps in early child development (ECD). We describe the iterative codesign and quality improvement process that informs the development of content for theThrive by Five International Program, localised for nine countries in Asia and Africa.DesignBetween 2021 and 2022, an average of six codesign workshops in each country were conducted in Afghanistan, Indonesia, Kyrgyzstan, Uzbekistan, Cameroon, the Democratic Republic of the Congo, Ethiopia, Kenya and Namibia.ParticipantsA total of 174 parents and caregivers and 58 in-country subject matter experts participated and provided feedback to refine and inform the cultural appropriateness of theThrive by Fiveapp and its content. Detailed notes from the workshops and written feedback were coded and analysed using established thematic techniques.ResultsFour themes emerged from the codesign workshops: local realities, barriers to positive parenting, child development and lessons learnt about the cultural context. These themes, as well as various subthemes, informed content development and refinement. For example, childrearing activities were requested and developed to promote inclusion of families from diverse backgrounds, encourage best parenting practices, increase engagement of fathers in ECD, address parents’ mental well-being, educate children about cultural values and help bereaved children with grief and loss. Also, content that did not align with the laws or culture of any country were removed.ConclusionsThe iterative codesign process informed the development of a culturally relevant app for parents and caregivers of children in the early years. Further evaluation is required to assess user experience and impact in real world settings.