What it does

Sine, square, triangle and saw at any frequency, binaural and isochronic modes, a sweep with loop, fine and coarse steps, volume
Libraries built in — Solfeggio, Rife, Schumann resonances, planetary (Cousto's cosmic octave), chakras, brainwaves, Tesla and angel numbers
Musical notes at A4 = 440 or 432 and other reference tunings; save your own presets
Tuner with pitch detection, FFT spectrum, and a sound-level meter with dBA, dBC and dBZ weighting, fast or slow, a gauge and running stats
Six themes and six launcher icons, from Settings

Microphone only, no internet permission. The microphone is used for the tuner and the meter while they are on screen; there is no permission that could carry a recording off the phone.

What it can reach

This is the whole list. Android prints the same thing under Settings › Apps › Permissions once the app is on your phone, and it was not written by us — check one against the other.

Microphone	The tuner and the level meter read it live — nothing is recorded
No internet permission	Nothing measured can be sent anywhere

Android 8.0 and up. Bought once, yours to keep: no account to make, no subscription, and no upgrade screen inside the app — the licence you buy unlocks it and every version after it.

Against the apps it replaces

The tone generators on Play carry ads or a subscription for the libraries; the meters are separate apps again. Generator, tuner, spectrum and meter are one app here
The libraries are built in, with what each frequency is for written beside it

Compared with Frequency Sound Generator, Function Generator, Sound Meter, gStrings.