I kept trying focus music apps and they all had the same problem: either they're just playlists with a "focus" label, or they want $10/month for rain sounds. Braintunes uses amplitude modulation at target brainwave frequencies — the same technique a 2024 Nature study found boosted focus brainwaves by 119%. Four modes (Focus, Relax, Sleep, Meditate), three intensity levels, sleep timer. Free, no ads, no subscription. Web, iOS, Android.
