Doppler Effect is a free Android application developed by José Antonio Gómez Tejedor and falls under the Education & Reference category. This app provides high-precision frequency analysis of sounds with an error rate of less than 0.04%. Users can define a frequency and the app calculates variations in the frequency with high accuracy. The app also plots the fundamental frequency versus time. Additionally, it records the frequency values as a function of time in a text file which can be emailed.

One of the unique features of the app is that it can measure sound Doppler Effect, which was published in the European Journal of Physics. More information about the app can be found in the reference: "Frequency analyser: A new Android application for high precision frequency measurement". Overall, Doppler Effect is a highly useful application for anyone working with sound frequencies who demands high precision.