Talk Diary

Talk Diary lets you reflect on your day by simply speaking. 100% private, voice-only journaling stored securely on your device.

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Inspiration

  • “Why don’t I feel happy even when I work hard every day?”
  • Social-media comparisons eroded my self-confidence, so I wanted a diary that measures progress against my past self, not strangers.
  • Typing felt tedious; the vision became a voice-only diary that remains private and friction-free.

What it does

  • Captures voice, removes silence with on-device VAD, and periodically uploads audio chunks to the OpenAI Whisper API (non-streaming).
  • Displays updated transcripts on-screen as each response returns, then stores entries locally in encrypted form.
  • Prompts reflective questions so users can articulate feelings—no typing, no cloud storage.

How we built it

  • Frontend: React Native + Expo (microphone via expo-audio); pastel “sunrise” palette for a calming UX.
  • Audio processing
    • react-native-vad trims silence.
    • Chunked uploads to Whisper; UI refreshes when each async result arrives.
  • Backend: Edge functions on Fastly, written in Fastify—handle config and key rotation only; diary content never leaves the device.
  • Prototyping: Screens sketched in Bolt, exported to Expo; AI code edits with Cursor accelerated boilerplate.
  • Subscriptions: Planned (RevenueCat) but not yet implemented.

Challenges we ran into

  • Building a near real-time STT UI without streaming support—managing async chunk uploads and incremental rendering.
  • Synchronizing microphone capture, VAD slicing, and UI updates while keeping latency low.
  • Working through App Store rules and metadata requirements on a tight schedule.

Accomplishments that we’re proud of

  1. Built my first-ever mobile app and reached TestFlight inside two weeks.
  2. Released and passed App Store review within the first month.
  3. Delivered a working non-streaming live transcription UI despite the complexity.

What we learned

  • The end-to-end flow of designing, building, and submitting a mobile app.
  • Practical App Store submission tactics and metadata hygiene.
  • Confidence that I can ship polished products under tight deadlines.

What's next for Talk Diary

  1. Personal Reflection Reports — offline summaries comparing current and past entries.
  2. Optional IAP subscriptions (7-day trial) via RevenueCat.
  3. watchOS / WearOS quick-capture widget.

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