FFTSensor

This is a free app that measures vibration using the acceleration sensor of a smartphone.
The frequency can be measured by displaying the power spectrum of vibration.
It is possible to analyze the vibration of the three axes of X-axis, Y-axis, and Z-axis.
Vibration data can be recorded, saved, and read.
The vibration frequency or rotation speed can be displayed.
The graph can be enlarged or reduced by pinching.