SUMMARY: GSLab addresses the need for effective image analysis tools in fluorescence microscopy by providing an open-source platform that enhances traditional phasor analysis with advanced features. Key capabilities include machine learning-based clustering, real-time monitoring, and quantitative unmixing of fluorescent species. Designed for both commercial and custom systems, GSLab provides researchers with comprehensive lifetime and spectral phasor image analysis tools to tackle complex biological problems. AVAILABILITY AND IMPLEMENTATION: The software is written as a MATLAB app. It is available for download at: https://doi.org/10.6084/m9.figshare.27921966. Example files and tutorials are also available: https://doi.org/10.6084/m9.figshare.28067108. For developers who wish to contribute please use: https://github.com/AlexVallmitjana/GSLab. A compiled Windows installer (does not require MATLAB) is available at: https://doi.org/10.6084/m9.figshare.28655276.