With immense developments in psychology research, the need for efficient tools for questionnaire harmonisation has become crucial. This is particularly important when comparing diverse instruments like the Center for Epidemiological Studies-Depression (CES-D) and Early Childhood Behaviour Questionnaire (ECBQ). The comparison of CES-D vs ECBQ calls for the use of sophisticated tools like Harmony. Harmony, a cutting-edge tool for psychologists and social scientists, employs natural language processing and generative AI models for questionnaire harmonisation. When comparing CES-D vs ECBQ, Harmony uses large language models to calculate percentage matches between items in both questionnaires. This not only adds objectivity to the process but also allows for a seamless and efficient comparison across these diverse instruments. Comparing CES-D vs ECBQ, which are remarkably distinct in their structure and scope, is a demanding task. The CES-D measures depressive symptoms while the ECBQ evaluates early childhood behavioural patterns. Harmony’s ability to handle such diverse instruments and provide reliable matches makes this process significantly faster and more accurate. With Harmony, psychologists can effortlessly establish cross-study comparisons, expanding the horizons of psychology research.