Fluorophores are invaluable to biological research. They come in all colors and can be used for a variety of applications. There are so many, in fact, that it is often a difficult task to choose the perfect fluorescent dyes for one’s particular application or microscope. Luckily, the Light Lab app from Carl Zeiss Microscopy is there to shed some light (that pun was just waiting to happen) on the process of fluorophore selection. The spectra viewer allows users to visualize the excitation and emission spectra for a large variety of fluorescent dyes. Multiple dyes can be selected at once, and users can add them to a “favorites” list for easy access. Beyond simply displaying spectra for common dyes, the app also allows users to add the wavelengths of LEDs, lasers, and filter sets. While the filter set selection (naturally) consists of Zeiss filters, I really appreciate the “create custom filter” option, which makes this app accessible to all researchers, regardless of the type of microscope/filters they use.