Twenty years of paper diaries, then an app that can't phone home

I kept a paper diary for twenty years. Then life got loud and the habit died for three years. Every journaling app I tried wanted an account, a subscription, and custody of the most unguarded text I produce. I'm an ML engineer. I know what "stored in the cloud" can mean, so I never wrote anything honest in them.

DailyVox is the app I built instead, and it started from one constraint: the app holds no network permission. Not "we don't upload." It can't upload. Everything runs on the phone: transcription with Apple's on-device speech, mood scoring, and a Digital Twin, a small model of your moods, topics, and the people in your life that can answer questions about your own entries.

You talk for about 42 seconds a day. That's the whole interface. Talking brought my habit back when typing couldn't.

Where it stands: live on iOS since March, free, interface in five languages. The iOS app's code is MIT on GitHub; the Twin engine is closed and ships inside it. An Android port is feature-complete but unreleased, because the entity graph depends on the speech recognizer capitalising names and I won't ship until I've tested that on real Samsung and Xiaomi hardware.

The bet I'd like pushback on: it stays free. No subscription, ever. For a diary, verifiable privacy plus a zero price is how the product earns the trust it needs, and monetising a vulnerable habit early would poison it. Naive? I've been wrong before.