Optical spectroscopy is widely used in non-contact materials analysis. Although laboratory bench-top spectrometers offer excellent resolution, range and sensitivity, their miniaturization is crucial for portable applications demanding indicative but instantaneous results. Among the recent developments in scaled-down spectrometers, an increasingly popular strategy is to use ‘reconstructive’ or ‘computational’ algorithm-based devices. Typically featuring spectral encoders with known optical responses, the measured electrical signals in such devices are combined to ‘approximate’ the incident spectrum through these algorithms. I will present an evolution of spectrometer miniaturization over the past 30 years and give examples of such disruptive concepts shaping future device technologies.