White noise & sleep sounds that actually work offline (no subscription)

White, brown and rain noise genuinely help many people sleep or focus — but sound apps are one of the most aggressively monetized categories, often gating the good sounds or the sleep timer behind a subscription.

What a good sound app needs

• A rich library you can mix (rain over brown noise, etc.).
• A reliable sleep timer with fade-out.
• Offline playback (no streaming, no data use overnight).
• A one-time price for something you use nightly.

I built Sereno as a pay-once sound machine: mixable sounds, timers, fully offline — no ads, no subscription.