The proliferation of Internet of Things has promoted a wide variety of emerging applications that require compact, lightweight and low cost optical spectrometers While substantial progresses have been made in the miniaturization of spectrometers, most of them are with a major focus on the technical side but tend to feature a lower technology readiness level for manufacturability. More importantly, in spite of the advancement in miniaturized spectrometers their performance and the metrics of real life applications have seldom been connected but are highly important. This review paper shows the market trend for chip scale spectrometers and analyzes the key metrics that are required to adopt miniaturized spectrometers in real life applications. Recent progress addressing the challenges of miniaturization of spectrometers is summarized, paying a special attention to the CMOS compatible fabrication platform that shows a clear pathway to massive production. Insights for ways forward are also presented.