FDI_tool is semi-automated tool for identification of forest disturbance based on Sentinel data. The tool is written in the Python programming language using an object-oriented approach. The input data are satellite images of Sentinel 2 on which four selected vegetation indices are calculated – NDVI, RSR, RVSI and REIP. The program is interactive and the final decision on forest disturbance is supported by graphs, time series, statistical indicators and colour representation of index values on the satellite image. The program is possible to use for any forest area with the character of a temperate zone. The results rather indicate the areas of significant change. Precise determination of the occurrence, causes and consequences of disturbance requires further detailed research.