Tone Generator is a free Android app developed by Jakob Robert that allows users to generate different tones by defining the wave form, frequency, and amplitude. The app supports four wave forms: Sine, Square, Triangle, and Sawtooth. The app also supports ring and amplitude modulation, which creates a tremolo effect for low modulation frequencies and interesting sound effects for higher frequencies.

One of the best features of Tone Generator is its visualization of the resulting sound wave as a graph. The graph is created using the open-source library MPAndroidChart, created by PhilJay and licensed under Apache 2.0. This visualization allows users to see the wave form of the tone they have created and make adjustments accordingly.

Overall, Tone Generator is a useful app for musicians, sound technicians, and anyone interested in sound synthesis. It is easy to use and provides a wide range of options for generating different tones. However, it should be noted that the app does not provide any additional features apart from tone generation and visualization.