Street Ledger

Street Ledger is a decentralized, high-integrity financial protocol designed to formalize and scale the world’s informal economies. In regions like South Africa and across the Global South, billions of dollars circulate in "street-level" credit—from spaza shop tabs to taxi fare IOUs—yet this value remains invisible to the global financial system. Street Ledger captures this untapped liquidity by transforming social trust into verifiable, on-chain data.

The Innovation: Predictive Trust The heart of Street Ledger is our proprietary Trust Prediction Engine. Unlike traditional credit scores that rely on stagnant bank records, our engine uses real-time P2P repayment velocity and social consensus to predict future creditworthiness. We are turning "my word is my bond" into a cryptographic asset. This allows users who were previously "unbanked" to build a digital reputation that can be leveraged for larger loans, institutional credit, and global opportunities.

Why This Wins the Global Stage We aren't just building a tracker; we are building a Liquidity Layer for the Informal Sector. By integrating high-performance technologies, we’ve solved the "triple threat" of P2P finance:

Sui (Performance): Utilizing Sui’s high-throughput architecture and object-centric model, Street Ledger handles thousands of micro-transactions with near-zero latency, ensuring that "paying back a friend" feels as instant as cash.

Yellow (Liquidity): We leverage the Yellow Network to ensure seamless cross-chain clearing and settlement, allowing informal debt to be settled in stablecoins without the friction of traditional fiat-to-crypto on-ramps.

Arc (Privacy & Security): By utilizing Arc’s secure infrastructure, we ensure that while trust scores are verifiable, the sensitive personal data of our users remains private and protected against exploitation.

Impact & Scalability Street Ledger is built for the next billion users. By bridging the gap between informal social contracts and DeFi (Decentralized Finance), we are creating a world where a vendor in Mahikeng can access the same financial tools as a trader in New York. We are not just competing for the top ten; we are building the infrastructure for the future of global, trustless commerce.

The Core Infrastructure Street Ledger is built as a multi-chain, privacy-preserving financial protocol. The backend is powered by Rust and deployed across a strategic stack of partner technologies to ensure it can scale to the "next billion" users in informal economies.

Sui Network (The Ledger Engine): We utilized Sui’s unique object-centric model to represent every debt relationship as a dynamic, on-chain asset. Unlike account-based chains, Sui allows us to store the "Trust Score" directly within the user’s identity object. We leveraged Programmable Transaction Blocks (PTBs) to batch micro-repayments and social endorsements into single, gas-efficient transactions, ensuring the protocol remains usable even for the smallest "street-level" debts.

Yellow Network (The Clearing Layer): To solve the liquidity gap, we integrated the Yellow Network SDK. Yellow acts as our cross-chain clearing house, allowing a user in one region to settle a debt in USDC while the recipient receives it in their preferred local stablecoin via Yellow’s state-channel mesh. This abstracts away the complexity of manual bridging and provides near-instant finality for peer-to-peer settlements.

Arc (The Privacy Shield): Financial data in social circles is highly sensitive. We used Arc’s opt-in privacy controls to ensure that while a user's aggregate Trust Prediction score is public and verifiable, the specific details of who they owe and why are encrypted. By utilizing Arc’s confidential transfer logic, we protect users from social credit-shaming while maintaining institutional-grade transparency for the trust score itself.

Technical Challenges & Solutions Building a bridge between "word-of-mouth" trust and cryptographic proof presented two major hurdles:

State Management Transition: Shifting from traditional SQL-style debt tracking to Sui Move required a complete rethink of ownership. We had to design a custom "Shared Object" architecture to handle debts where two parties need to mutually sign off on a repayment without creating a bottleneck in consensus.

Latency vs. Truth: In informal markets, internet connectivity is often intermittent. We faced the challenge of ensuring "offline-first" integrity. We solved this by implementing a local-first shadow ledger that uses cryptographic signatures to queue transactions, which are then settled atomically on Sui the moment the user is back online.

The "Hacky" Innovation: Shadow Reputation A particularly notable feature we implemented is what we call "Shadow-Object Syncing." To keep the UI lightning-fast (sub-200ms) on our Flutter mobile frontend, we created a temporary off-chain state that mimics the Sui Move objects. This "hack" allows users to see their updated trust score instantly after a payment, while the actual blockchain settlement happens asynchronously in the background. This creates a Web2-like user experience on top of a heavy-duty Web3 backbone.