This is a waveform generator app for Android, capable of producing four different functions: Sine, square, triangle and sawtooth.

In addition to everything offered in the free version of this app, you can also send the waveforms produced by this app to separate headphones / speakers (different channel driving the left and right headphone / speaker), and activate 3 different preset buttons, for frequently used channel modes / frequencies combiations.

With this application you can produce waveforms in the range of 20 Hz to 20 kHz (for more info check the "Help" tab in the app's preferences) in two different ways.
Either set a specific frequency and have it play constantly, or dynamically change the output frequency by swiping your finger on the upper half of the screen.

Before buying this app, please make sure that you have tried out the free version, and that it fits your needs.

Note that by splitting this app in free and paid versions (instead of an in app purchase), there is no need for this app to connect to the internet (nor does it require a permission to do so). Therefore this app is fully functional offline.