Currently, laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICP-MS) is a prominent and powerful method for in situ isotopic analysis. It provides high precision and spatially resolved isotopic information in solid samples. Data reduction of LA-MC-ICP-MS is inherently challenging owing to the severe mass spectral interferences and complex mass bias behaviors that occur during the analytical process. In this study, we present new freeware software, Iso-Compass, for isotope data reduction in LA-MC-ICP-MS. This software provides highly practical functions, including a simple data input interface, manually defined selection of laser and background signals, background correction, internal or external mass bias correction, interference correction, visual data presentation, and formatted data output. These functions can achieve easier and efficient reduction of LA-MC-ICP-MS data. The flexible formula editing mode enables Iso-Compass to be used in different isotope systems, thereby offering the potential to become a universal isotope data reduction platform for the geochemical community. Moreover, we present two examples (radiogenic Sr isotope analysis and stable Zr isotope analysis) to demonstrate the effectiveness of Iso-Compass.