FlowRent

Problem Statement

FlowRentA global pay-as-you-go vehicle rental app with passport-based KYC via SelfXYZ, eliminating traditional FX and enabling seamless cross-chain PYUSD payments through LayerZero.Our app lets you rent vehicles anywhere in the world and pay only for what you use. Passport-based KYC via SelfXYZ ensures instant verification while giving you control over which details (name, country, age) are disclosed. Traditional foreign exchange hassles are eliminated with PYUSD, and payments are streamed via Sablier and settled across chains using LayerZero.Traveler Scenario: Business Trip from Mumbai to San FranciscoPre-trip PreparationYou download the FlowRent app and complete one-time verification using passport via SelfXYZ.Only your name,country and age is disclosed.Arrival in San FranciscoUpon landing, you select a Tesla Model 3 for going to the hotel.Seamless Rental ProcessYour passport verification is instantly recognized across chains via LayerZero.You deposit an initial amount of PYUSD , which is held in the FlowRent escrow contract.You unlock the Tesla and begin your rental.Pay as You GoAs you drive, PYUSD payments stream from the deposit to the vehicle owner via Sablier.When driving in congested areas, the rate automatically adjusts based on telemetry data usingFfrom Tesla.Your dashboard shows the remaining deposit in real time.Return and SettlementAfter completing the trip, you return the vehicle to the designated area.The final odometer reading and conditions are recorded via the FlowRent Oracle.The remaining deposit is immediately returned to the connected wallet.You receive a dynamic NFT based receipt for corporate expense reporting.BenefitsNo need for international credit cards or currency exchangeNo waiting for security deposit refundsPay-per-minute pricing rather than full-day chargesTransparent, immutable record of all transactionsStreamlined expense reportingThis cross-border rental experience demonstrates how FlowRent eliminates traditional friction points in international vehicle rentals while providing enhanced security and transparency for both renters and vehicle owners.

Solution

We started with the Self Protocol + LayerZero boilerplate, using it to build passport-based KYC and QR code verification. Proof details are sent from Celo to Arbitrum Sepolia testnet using LayerZero. Payments are made in PYUSD, with an initial deposit held in an escrow contract. Sablier powers the pay-as-you-go streaming payments, and LayerZero handles all cross-chain settlements. The whole flow is stitched together using existing templates and partner integrations for fast prototyping.During development, we encountered a significant challenge: our original contract exceeded the EVM contract size limit of 24,576 bytes by almost double (43,332 bytes). This error halted our progress. Then we implemented a two-phase split contracts(still the size was around 27k bytes), then further breaking down into Extensions to handle specialized functionality.Key Benefits from Sponsor Technologies Self Protocol:Frictionless global KYC through passport scanning, eliminating repetitive verification across countries Granular disclosure control lets users share only necessary attributes (age for driving requirements, country for compliance) Cross-border verification without local documentation requirements QR code verification takes seconds compared to traditional rental KYC processes that take 15+ minutes PYUSD:Removes currency conversion fees that typically add 2-5% to international rentals Same-currency transactions across all global locations eliminate exchange rate surprises Regulated stablecoin ensures rental deposits maintain consistent value Instant deposit returns compared to 7-14 day traditional rental refund timelines Sablier:True by-the-minute usage billing versus traditional daily/hourly minimum charges Stream stops automatically when vehicle is returned, preventing billing disputes Real-time payment visibility shows exact spending during the rental No overpaying for unused time (average savings of 30% compared to traditional rentals) LayerZero:Connects identity verification from Celo to rental operations on Arbitrum without user complexity Ensures verification and payment status consistency across chains Enables the same user experience regardless of which chain the user or vehicle provider operates on Single transaction history view aggregates cross-chain activities for simplified record keeping