A growing area of research focuses on the relationship between ocular light exposure and the non-visual responses. In order to accelerate research on this topic and improve building design, reliable spectral simulation tools are needed. This study aims at validating two of them, Lark and ALFA, by comparing their outcomes against daylight measurements. The goal is to assess how reliable these tools are in predicting spectral irradiance under different skies for indoor spaces. While spectral irradiance can in principle be simulated with a similar accuracy as for photopic values, there are some caveats in the current versions of both platforms.