Alamar Blue is a reagent that tests for cell viability that contains a blue indicator called resazurin. The reagent is cell permeable and non toxic. It is commonly used to test for cell viability, but can also be used for cell development assays and cytokine bioassays. Alamar blue is a oxidation-reduction indicator and the dye turns from blue to pink when the redox reaction occurs in mammalian cells and bacteria.