Harmonising questionnaires can shed light on interrelated psychological constructs, allowing an in-depth insight into an individual’s mental health. A critical area of interest among mental health researchers is the examination of shared concepts in CES-D and RSES. CES-D vs RSES analysis often uncovers correlations in depression symptoms and self-esteem measures. With various researchers targeting similar comparisons, it can be magnified through the use of Harmony, the innovative software specifically created to facilitate the harmonisation process. With Harmony, psychologists and social scientists can compare CES-D and RSES questionnaires with a precision unachievable through manual comparison. CES-D vs RSES harmonisation becomes a push-button task rather than a time-consuming chore. Harmony, with its natural language processing and generative AI models, can identify similarities or differences between questionnaires possibly missed by the human eye. In addition, Harmony expands on the capability of cross-cultural comparisons as it can interpret questionnaires in different languages. Harmonisation not only ensures the comparability of data but also enriches the quality of the information gathered. In the case of CES-D vs RSES, Harmony can exhibit how the aspects of depression and self-esteem interact and influence one another, contributing to a holistic understanding of mental health. As CES-D and RSES are widely accepted psychological instruments, using Harmony’s harmonisation capability in this context can lead to more comprehensive studies and thus, a more nuanced understanding of human psychology.