Mieter App
German tenant-rights companion. 8-city Mietspiegel, Mietpreischeck, Nebenkostenprüfung, PDF export.
The problem
A Mieterbund membership costs ~€70 per year and still leaves tenants Googling §573c deadlines at 11 PM the night before they need to respond to a Kündigung. The legal data is public, the math is deterministic, and the offline case is the most common one. We built Mieter App because a tenant-rights calculator does not need a backend, a subscription, or a data broker.
How we built it
- 01MietspiegelRepository with curated JSON data for 8 cities, loaded locally, queried by Postleitzahl and Baujahrsklasse.
- 02Mietpreischeck flow that runs §556d BGB validation and auto-generates a PDF Rügeschreiben via share_plus — no print dialog, straight to WhatsApp or email.
- 03BetrKVRulesEngine: 22-category Nebenkosten classifier + six rule checks, fed by a dynamic entry UI and a Widerspruch-PDF generator.
- 04Seven Mieterrechte-Themen with four Musterbriefe (copy-to-clipboard) and a §573c BGB Kündigungsschutz calculator honoring the 3.-Werktag rule.
Outcome
Five phases shipped, 98 of 98 tests passing, zero analyzer warnings, SharedPreferences-based theme persistence, explicit Haftungsausschluss. Built end-to-end in a single focused development pass.
Stack
Flutter + Dart. SQLite for local persistence. share_plus for PDF / text export. No backend, no accounts, no tracking.
Next up
Phase 4b OCR for scanned Nebenkostenabrechnungen, plus optional Phase 6 launch prep once store credentials swap.