Case study · 02/15

Flash-Destock

A hyperlocal flash-deal marketplace: shops clear surplus stock, customers reserve with a QR pass.

Category: Mobile apps · Web applications · E-commerce
Year: 2026
Status: Google Play · closed testing
Languages: FR · EN

Flash-Destock — deal page with countdown and stock

Flash-Destock — a bakery deal with allergens and use-by date

Flash-Destock — the QR pass shown at the till

Overview

Flash-Destock launches first in Paris. Local shops, restaurants and bakeries publish time-limited discounts on surplus stock and food. Customers browse deals nearby and reserve a free QR pass, then pay in the shop; the merchant scans the pass at the till to confirm the sale. One public Android app serves customers and merchants, and a private admin app is used for moderation.

Our solution

A Flutter monorepo (two apps, four shared packages) on a Supabase backend: Postgres with PostGIS for nearby search, business rules in database functions protected by row-level security, Edge Functions for push notifications and Play Billing verification, and Firebase for messaging, crash reports and shared-deal web pages.

Key features

01
Deals nearby by arrondissement, with search, categories and a map
02
Live countdown, stock bar and legal reference-price note on every deal
03
Allergens (14 EU majors) and use-by dates on food deals
04
Offline QR pass, scanned at the till with idempotent redemption
05
Merchant space: 4-step shop registration with SIRET check, offers, stats funnel, staff
06
Private admin app with mandatory two-factor sign-in and audited moderation

Engineering highlights

0183 row-level security policies; roles always read from the server, never the client
02QR secrets kept in secure device storage — the server only stores their SHA-256 hash
03Redemption with row lock, conditional stock decrement and idempotency key: stock can never go negative
04About 296 automated tests, including 132 backend tests running the real SQL migrations