In environmental conservation and management, analysing soil, climate, and stand data within forest ecosystems is crucial for understanding ecological dynamics, projecting changes, and developing sustainable forestry practices. Often, these data are scattered and unintegrated, complicating their use in modelling and analysis. Current tools lack modular integration of soil, climate, and stand data at large and diverse NFI datasets like International Co-operative Programme (ICP) scale (12,000+ sites). ForestScope bridges this gap by automating harmonization of ICP’s Level I/II datasets, together with soil and climate data, which is essential for informed decision-making in forest management. ForestScope introduces an open-source framework designed to systematically organize, extract, and harmonize fragmented soil, climate, and stand data from ICP datasets. It includes comparative analyses of International Soil Reference and Information Centre (ISRIC) and Harmonized World Soil Database (HWSD) soil datasets, and assessments of Inter-Sectoral Impact Model Intercomparison Project (ISIMIP) climate models and Climatologies at High resolution for the Earth’s Land Surface Areas (CHELSA) against observational data, selecting HWSD v2.0 and CHELSA as optimal for ICP data gaps. Additionally, ForestScope integrates a vegetation model enhancing National Forest Inventory (NFI) data processing, thus improving forest ecosystem modelling. This advancement deepens our understanding of forest dynamics and supports more effective management strategies.