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By Tilt Pay
Tilt Pay is a live mobile payment app (1,431 users, $39K processed, 211 Tap-to-Pay NFC transactions) migrating its full settlement infrastructure to Stellar. Today, payments settle through a centralized backend with limited cross-border coverage and no yield or swap capability. After this integration, the same user flows execute natively on Stellar with USDC settlement, automated yield, and in-app swaps. The integration stack is backed by a formal threat model and production observability layer deployed before any mainnet exposure.
This submission integrates four building blocks from the Integration List. Each feature maps to a user action, an onchain event, and a Stellar ecosystem metric.
1. Embedded Non-Custodial Wallets (Privy + Stellar SDK)
Stellar Usage: Privy creates Stellar wallets invisibly at signup (email, social login, passkeys). Stellar SDK handles transaction construction and submission.
Impact: Non-crypto users onboard without seed phrases or signing prompts.
Ecosystem metric: Active wallets, returning wallets.
2. Tap-to-Pay Settlement on Stellar
Stellar Usage: Contactless NFC payments settled as USDC transactions on Stellar with standard network finality. Soroban contracts handle payment logic, fee deduction, and idempotency.
Impact: Instant settlement at reduced fees vs. card networks for merchants and freelancers.
Ecosystem metric: Stablecoin transfer volume, payment volume, active senders/recipients.
3. Fiat On/Off-Ramp (Bridge)
Stellar Usage: Bridge API connects USD/EUR virtual bank accounts (Noah) to USDC on Stellar across ACH and SEPA Instant rails.
Impact: Users deposit and withdraw fiat seamlessly, no crypto knowledge required.
Ecosystem metric: Stablecoin supply, on/off-ramp activity, bridge inflows.
4. USDC Yield (DeFindex)
Stellar Usage: DeFindex vaults on Stellar for automated yield strategies, same approach as Meru and Beans.
Impact: Passive income on idle USDC balances, increasing user retention.
Ecosystem metric: TVL, stablecoin utilization, contract invocations.
5. In-App Swap (Stellar Broker)
Stellar Usage: Stellar Broker routes swaps across Stellar DEX, Soroswap, and Aquarius.
Impact: Users swap currencies without leaving the app, full experience stays on Stellar.
Ecosystem metric: DEX volume, path payments.
$124.0K
Tilt Pay is live on iOS (since June 2026, 32% of users) and Android (since April 2026, 68%) with real users and early monetization:
Users: 1,431 registered users, sustained organic growth of 25+ new users per day with zero paid acquisition.
Volume: $39,000 in Total Payment Volume processed.
Transactions: 211 completed contactless Tap-to-Pay transactions.
Revenue: $59.76 from Tap-to-Pay fees and Virtual Bank Account issuance, monetizing from day one.
Banking: Live partnership with Noah for USD/EUR virtual account issuance, fully operational.
B2B: Signed contract with a Canadian fintech to integrate our payment rails into their banking app, projecting 2,000+ new users per month. https://drive.google.com/file/d/1DotTgRiBa3xmnflVeoGWDTxC0AJHa4yu/view?usp=drive_link
On-chain proof and detailed metrics:
https://drive.google.com/file/d/1dz5QIkJC1x2B1EU4BlOthDIkS0xsCHAX/view?usp=sharing
Focus: Embedded wallets, Tap-to-Pay smart contracts, fiat on/off-ramp. The technical architecture, data flows, and integration design for all four building blocks (Privy, Bridge, DeFindex, Stellar Broker) have been documented in advance and are available on GitHub: github.com/e2liotp/tiltpayappstellar. This tranche constitutes the entire technical foundation and payment core of Tilt Pay on Stellar.
Deliverable 1: Proof of Concept + Privy Wallet Integration
Description:
Starting with a minimal PoC demonstrating end-to-end wallet creation and first USDC transaction on Stellar testnet, this deliverable scales into full production integration of Privy for embedded non-custodial wallet creation. Users create a wallet via phone number, email, or social login — no seed phrase, no blockchain UX. Privy handles key management and signing delegation. Tilt Pay backend builds and submits transactions via Stellar SDK. Implementation covers: wallet creation flow, key storage model, transaction signing pipeline, wallet recovery, and session management. All code unit-tested.
Technical specs: Privy SDK + Stellar SDK v12+, React Native (iOS + Android), Stellar Horizon for broadcasting.
How to measure completion:
PoC wallet created via phone number on Stellar testnet with no seed phrase exposed. USDC test transaction confirmed on-chain. Full wallet creation functional via phone/email/social on testnet and mainnet staging. Transaction signing pipeline tested with 100+ transactions. Unit test coverage >80%. No seed phrases exposed at any point in the flow.
Estimated date of completion: October 15th 2026
Budget: $21,600
Deliverable 2: Soroban Smart Contracts for Tap-to-Pay (NFC/BLE)
Description:
Design, develop, test, and deploy Soroban smart contracts enabling contactless Tap-to-Pay transactions in USDC on Stellar testnet. Contracts handle: payment initiation, USDC transfer between wallets, fee deduction (75–100 bps), idempotency (nonce-based duplicate prevention), and transaction status events. BLE discovery and NFC handshake are handled in the React Native layer; Soroban handles settlement. Full contract test suite included.
Technical specs: Soroban SDK (Rust), Stellar Testnet, React Native BLE/NFC libraries (react-native-ble-plx, react-native-nfc-manager).
How to measure completion:
Smart contracts deployed on Stellar testnet. 50+ Tap-to-Pay test transactions processed end-to-end (device A → device B) with confirmed on-chain settlement. Transaction finality <5 seconds in 95% of cases. Fee deduction verified correct across all test transactions. Contract test coverage >90%.
Estimated date of completion: November 4th 2026
Budget: $17,800
Deliverable 3: Bridge Integration — Virtual Bank Accounts (vIBANs) + USDC Settlement
Description:
Full integration of Bridge (by Stripe) API to issue USD and EUR virtual IBANs for Tilt Pay users. Covers: vIBAN creation per user, fiat deposit detection (ACH/SEPA), automatic USDC minting on Stellar via Bridge after fiat receipt, USDC-to-fiat withdrawal flow (user requests withdrawal → Bridge liquidates → fiat sent via SEPA/ACH). Includes webhook handling for deposit/withdrawal status updates and reconciliation logic.
Technical specs: Bridge API (REST), Stellar Horizon for USDC monitoring, Stellar SDK for USDC transfers, webhook server (Node.js).
How to measure completion:
vIBANs successfully created for 10+ test users. EUR SEPA deposit detected and USDC minted on Stellar testnet within standard Bridge processing time. USDC withdrawal successfully processed to a test IBAN. Webhook events handled without data loss. Integration tests pass with zero failed transactions in a 25 run suite.
Estimated date of completion: November 26th 2026
Budget: $15,600
Focus: DeFindex yield, Stellar Broker swaps, full end-to-end testnet validation across all features.
Description:
Integrate DeFindex vault protocol on Stellar to enable automatic USDC yield for users. Flow: user activates yield feature (single on-chain authorization) → Tilt Pay backend deposits user USDC into DeFindex vault → yield accrues automatically → user sees real-time APY and accumulated earnings in app → withdrawal triggers instant redemption from vault. No DeFi complexity exposed. Includes: vault deposit/withdrawal logic, yield calculation display, real-time APY fetch from DeFindex, user activation/deactivation flow, and error handling for vault unavailability.
Technical specs: DeFindex SDK/contract interface on Stellar testnet, Stellar SDK, React Native UI components.
How to measure completion:
USDC deposits into DeFindex vault functional on testnet. Yield accrual visible in app UI within 24h of deposit. Withdrawal processed successfully in <30 seconds. APY displayed matches DeFindex published rate. Tested with 20 deposit/withdrawal cycles without errors.
Estimated date of completion: December 4th 2026
Budget: $16,200
Description:
Integrate Stellar Broker to enable direct asset swaps on the Stellar DEX within the Tilt Pay app. Users convert between supported currencies (USDC/XLM/EURC) without leaving the app. Covers: quote fetching (best price via Stellar DEX path payment), swap execution, slippage tolerance settings, transaction confirmation UI, and swap history. Full experience remains on Stellar.
Technical specs: Stellar Broker API, Stellar SDK path payment operations, React Native.
How to measure completion:
Swap quotes returned in <3 seconds. Swap transactions executed on Stellar testnet with correct amounts. Slippage tolerance enforced (transaction fails if exceeded). Tested with 15+ swap cycles across USDC/XLM/EURC pairs. Exchange rates match Stellar DEX live quotes at time of execution.
Estimated date of completion: December 17th 2026
Budget: $13,300
Description:
Before any mainnet exposure, this deliverable covers the full security and observability layer. (1) Formal threat model documenting all identified attack vectors: replay attacks (nonce validation on Soroban contracts), smart contract vulnerabilities (reentrancy, integer overflow), Privy key compromise scenarios, Bridge/DeFindex API failure modes, and front-running on Stellar DEX swaps, each with documented mitigations. (2) Internal security checklist reviewed against threat model and signed off. (3) Production monitoring and alerting infrastructure deployed on testnet: transaction failure rate alerts, settlement latency tracking, yield discrepancy detection, wallet creation failure monitoring, and Soroban contract event logging. All observability tooling verified live on testnet before Tranche 3 begins.
How to measure completion:
Threat model document published on GitHub covering identified attack vectors with documented mitigations. Internal security checklist completed and signed off. Monitoring dashboards operational and alerting configured for all critical paths. Observability infrastructure verified on testnet with documented test results.
Estimated date of completion: December 31th 2026
Budget: $16,500
Focus: Smart contract audit and remediation, mainnet deployment post-audit, and professional user testing.
Description:
Leverage the Stellar Audit Bank credits (or Almanax if not eligible) to conduct a formal security audit of all Soroban smart contracts developed in Tranches 1 and 2. Remediate all issues identified during the audit before any mainnet deployment. Following remediation, publish clean and complete integration documentation on the project GitHub and/or Gitbook, covering: Stellar wallet architecture, Soroban contract code (open source), and integration guides for each partner (Privy, Bridge, DeFindex, Stellar Broker).
How to measure completion:
Audit completed and audit report received. All critical and high-severity findings remediated. 3+ integration guides published on GitHub/Gitbook. Remediated contracts reviewed and cleared for mainnet deployment.
Estimated date of completion: January 10th 2027
Budget: $8,000
Description:
Deploy all audit-cleared Soroban contracts and backend infrastructure to Stellar mainnet. Configure production Privy environment, Bridge production API, DeFindex mainnet vaults, and Stellar Broker mainnet. Staged rollout: internal team first, then beta group, then open access. Monitoring and alerting setup (transaction failures, latency spikes, yield discrepancies).
How to measure completion:
All contracts live on Stellar mainnet. 50 first real users onboarded with functional wallets. 25+ real Tap-to-Pay transactions processed. Zero critical production bugs in first 2 weeks.
Estimated date of completion: January 27th 2027
Budget: $8,500
Description:
Deploy all audit-cleared Soroban contracts and backend infrastructure to Stellar mainnet. Configure production Privy environment, Bridge production API, DeFindex mainnet vaults, and Stellar Broker mainnet. Staged rollout: internal team first, then beta group of existing users, then open access. All monitoring and alerting infrastructure built in Tranche 2 activated for production traffic.
On-chain footprint registered at award time: deployed Soroban contract addresses and Stellar wallet addresses generated via Privy, all published on project GitHub and independently verifiable on Stellar Explorer.
How to measure completion:
All Soroban contracts deployed on Stellar mainnet, contract addresses published on project GitHub and verifiable on Stellar Explorer. Minimum 50 Stellar wallets created via Privy, wallet addresses published on GitHub and verifiable on Stellar Explorer. Minimum 25 real Tap-to-Pay transactions processed on Stellar mainnet, transaction IDs published on GitHub and verifiable on Stellar Explorer. All metrics measured over a 30-day window starting from the date all Soroban contracts are deployed on mainnet. Monitoring and alerting infrastructure operational in production with documented incident log for the measurement window.
Estimated date of completion: February 5th 2027
Budget: $6,500
Not asked for SCF#45
Elliot Boyer - CEO
Expertise: Product Strategy, Go-To-Market, B2B Payment Infrastructure
Experience: Ex-CEO of Crypto Initiate (30 clients, 130K+ article views in 6 months). Founded Tilt Pay: launched Tap-to-Pay infrastructure, orchestrated BaaS integrations (Noah virtual accounts), managed Apple App Store fintech deployment.
linkedin.com/in/elliot-b-a4b3b62a7 | x.com/crypto_e2liot
Alexandre Chane-Law - CTO
Expertise: Blockchain Architecture, Backend Development, Web3 Infrastructure
Experience: Ex-software engineer at Nomi (Y Combinator W25). Co-founded Pay Consent, incubated by Binance Labs.
linkedin.com/in/alexandre-chane-law | github.com/NargusS
Florian Warther - Lead Developer
- Expertise: Mobile Development, SDK Integration, Frontend Architecture
- Experience: Ex-CTO of Crypto Initiate. Leads mobile development and technical architecture for Tilt Pay across iOS and Android.
- Links: linkedin.com/in/florian-warther-5371b825b | github.com/2Fl00rian6
Hackathons:
- 1st place, Paris Blockchain Week 2023 (Pay Consent)
linkedin.com/feed/update/urn:li:activity:7045044676625620992
- 2nd place, Superteam France / Colosseum Cypherpunk
Events:
- Tilt Pay presented at ETHCC 9 (Cannes, 2026)
linkedin.com/posts/elliot-b-a4b3b62a7_vlog-ethcc-9-see-you-next-year-activity-7445949531302596608
Elliot
No other submissions.