Palavra: a daily devotional app for Brazil
Generic devotional apps do not speak to a person’s own church or worries, and AI chatbots can invent Bible verses. Palavra writes each day for the reader and only quotes passages it retrieved from the Bible text.
The problem
Many readers want a short devotional that fits their own church and the worry they carry today, and many prefer to listen rather than read. A general-purpose chatbot can answer faith questions, but it can also quote verses that do not exist.
What was built
- A new devotional every day — verse, reflection and prayer — for the reader’s church and chosen topics, from anxiety and family to finances and grief.
- Narration with the phone’s own Portuguese voice at any speed, with lock-screen controls and the current word highlighted.
- Questions by typing or speaking, organised as conversations; every cited verse opens its full chapter.
- Verse-of-the-day cards for WhatsApp, local reminders, and a Palavra+ subscription on Google Play with a free tier that keeps the daily devotional.
AI that cannot invent Scripture
- All 179,485 passages of two Portuguese translations are indexed as vectors with a multilingual embedding model that runs locally in Rust, so search has no per-query fees.
- The language model may cite only the passages retrieved for the question. References are checked before anything is shown, and the verse text on screen comes from the database, not from the model.
- If a service is missing — the model, the embeddings, Google sign-in — the API says so with an explicit error instead of quietly answering worse.
- Crisis questions return the CVV 188 helpline before any quota or subscription check, and never count against the free limit.
App, backend and billing
- Flutter app with Riverpod, go_router and a Drift local database; the API client is generated from an OpenAPI contract.
- Rust API and worker with PostgreSQL 17 and pgvector; the worker prepares each day’s devotionals and enforces data retention.
- Google Play Billing without a third-party wrapper: purchases are verified on the server, and store notifications arrive through Pub/Sub with duplicates ignored.
- Explicit consent before church and topics leave the device, real account deletion and export, and analytics without personal fields.
The landing page
palavradevocional.com is hand-written HTML and CSS in Brazilian Portuguese, with help, privacy, terms and account-deletion pages, served by the same server as the API. The footer credits Shelf Compass as the maker and links to My Little Indie Studio.
Status and limits
Published on Google Play for Android, in Brazilian Portuguese only. AI answers can contain mistakes; the quoted verses always come from the Bible text. The app was published in October 2026, so no store numbers are quoted.
- Palavra: Devocional e Bíblia — A daily devotional app for Brazil, in Portuguese: written for the reader’s church and life topics, read aloud by the phone, with faith questions answered only from real Bible passages.
- Audience
- Evangelical Christians in Brazil who want a short daily devotional and often prefer listening to reading
- Stack
- Flutter with Riverpod and Drift; Rust (axum, sqlx) + PostgreSQL 17 with pgvector; OpenAPI-generated client; Docker Compose and Caddy
- AI models
- DeepSeek for devotionals and answers; multilingual-e5-small embeddings on ONNX Runtime for Bible search; on-device text-to-speech
Custom applications and their landing pages are studio services — see the service