Rheological testing of soft materials aims to characterize them through a complex combination of elastic and viscous properties. Its fundamental idea is to apply a force and register the resulting deformation of the material. These tests have applications in a wide range of domains from adjusting oil drilling muds for different rock strata to developing fast-drying paints and quality control in food processing. Yet, visual-interactive means for the explorative analysis of the resulting data are scarce if they exist at all. Hence, we present $VAOS$ - an open-source visual analysis software for exploring the complex rheological properties of soft materials subjected to oscillatory tests. $VAOS$ offers a specific focus on the visual analysis across multiple samples and test runs at once, which is currently not well supported by existing software. We showcase the utility of $VAOS$ in a usage scenario and two expert interviews, effectively demonstrating the improved ability of scientists to swiftly obtain a rheological fingerprint of complex materials.