Talks, Keynotes & Speeches
Zero Bars: An Offline-First POS in Flutter.
Architecture, production code and battle-tested lessons for building a mobile Point-of-Sale in Flutter that completes sales and processes card payments even when network signal completely vanishes.
Slide Deck Preview
A selection of key slides from the presentation. Download the complete 30-slide PDF deck with high-res sequence diagrams and in-depth speaker notes below.
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What's Covered in the 30 Slides
Core engineering concepts discussed during the keynote, from UI state decoupling to offline ledger accounting.
01 · The POS as the Original Mobile Device
From 1970s mechanical carbon-copy imprinters ("ritsch-ratsch") to wireless GSM terminals, Square's headphone jack reader, and modern custom Android terminals (PAX, Verifone). Why reliability shifted from telecom carriers to application software.
02 · Selling at Zero Signal
Handling high-friction environments: in-flight sales at 35,000 feet, crowded street markets, and packed convention centers with saturated cell towers. Rule #1: customers will never wait for a signal before paying.
03 · The Local Database is the Single Source of Truth
Architectural paradigm shift: the UI never waits for an API call before rendering. The UI writes directly to reactive local SQLite (Drift), the screen updates immediately at 60 fps, and the background sync engine catches up when possible.
04 · Outbox Pattern & Idempotency
Atomic local SQLite transactions coupling order creation and outbox queuing. Client-generated IDs (technical UUIDv4 + human-readable device receipt numbers). Idempotency keys on every payload to safely survive timeouts and retries.
05 · Money & Conflict Resolution
Money is never a double: strict integer arithmetic in cents (avoiding IEEE 754 floating-point pitfalls). Lightweight conflict resolution using append-only ledgers and stock deltas rather than heavy generic CRDTs.
06 · Stripe Terminal in Offline Mode
Deep-dive into Stripe's offline Terminal SDK: local payment capture on disk, create, collect, and confirm without connectivity, native Flutter MethodChannels, and background forwarding upon reconnection.
Esperienza & Social Proof
Track Record & Past Keynotes
«The Truth about eCommerce» · Berlin, San Francisco, New York
Event series and masterclass created and hosted for the Berlin Retail & eCommerce Meetup at WeWork Berlin. Live international sessions and recording of Experience This Ep. 17 in San Francisco. Average participant rating: 5.0 out of 5.0.
SMAU Milan · Omnichannel & Proximity Retail
Keynote speaker at SMAU Milan 2019 covering omnichannel commerce platforms, proximity payments and modern checkout ergonomics.
GreenMindAI Catania Hackathon 2025
Awarded among the top three projects for Briller.AI, focusing on automated industrial energy efficiency.
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