A new generation of microplate absorbance readers captivates with their small footprint and innovative set-up. Within seconds, a compact system without moving parts composed out of 4 LEDs and 96 photodiodes allows the simultaneous reading of the individual signals from a 96-well plate. The built-in assay protocol is performed by means of a software which controls the reader via USB. Here we demonstrate the adequacy of the reader for typical cell-based applications like cytotoxicity testing or proliferation assays. The ultra-compact absorbance reader is particularly useful for standardized routine assays, as it provides high robustness and reliability, while minimizing susceptibility to errors.