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By Coala Pay Billy Wallet
Coala Pay will adapt the use of its own wallet, Billy, to facilitate last mile payments. Billy will be brought onto mainnet, and utilize a QR code reconciliation system and vendor network to facilitate payments to Stellar Aid Assist transactions.
Coala Pay Billy Wallet: brought from Proof of Concept through mainnet to ensure offline capacity, QR code reconciliation system, and relayed with Stellar Aid Assist
Stellar Aid Assist: Ability to run offline cash payments that are recorded on chain, and a fully integrated end to end system with Billy
Maybe in the future, but not in this submission
$60.0K
Coala Pay provides offline reconciliation of group transfers from Stellar’s disbursement platform of 2500-5000$. This offline reconciliation will be faster, less expensive and more efficient than utilizing regular bank transfers, or other forms of money transfers in these environments. This allows for greater financial inclusion in these locations, particularly those receiving humanitarian aid. Performance metrics will be detailed out in a report highlighting these gains.
Billy Wallet is utilized for last mile payments and fully functional end to end system with Stellar integration, and is able to be deployed in additional environments/locations with ease.
Coala Pay is already working in some of the toughest aid environments. Through enabling Stellar Aid Assist for the last mile, the Billy Wallet (and Coala Pay) can continue to access a variety of different locations and securely and efficiently work in low internet settings across the world. Additionally, client requests for this type of product development will continue to penetrate in both depth and breadth with those clients, as well as introduce possible new markets.
So far with Coala Pay, our clients/users are or will be enabled to do the following, with additional use cases developing regularly:
Fund Local Partners
Send grants to local implementing organizations without the delays and costs of traditional banking. Track milestones, automate disbursements, and maintain transparent oversight.
Deliver Cash to Households
Manage household cash transfer programs with reduced overhead. Simplify distribution, strengthen verification, and create tamper-proof records of delivery.
Handle Vendor Payments
Pay suppliers and service providers without excessive fees or delays. Maintain value despite local currency fluctuations.
Coala Pay in 2024 took on four large NGO clients across three countries, and is rapidly expanding to more countries each month. The payment volume has increased, month on month, since December of 2024.
Offline payments is a logical next step at continued request of our clients/product users.
Objective: Define system architecture, development environment, and sprint goals.
Design high-level architecture (Smart contracts, Web app, Mobile app).
Define user stories and acceptance criteria.
Define backend reutilization of Stellar Distribution Platform (SDP) for online payments to beneficiaries that own a phone.
Proof of Concept (POC) for setting up Stellar Testnet, Ethereum Testnet, APIs
Establish CI/CD pipeline for continuous testing, security audits and Cloud deployment.
2. Core Blockchain & Identity System
Objective: Implement basic blockchain functionalities and beneficiary identity tracking.
Develop Soroban smart contract for NFT-based beneficiary identity.
Implement QR Code generator (mapping NFT Token IDs to beneficiaries).
Develop web app for NFT minting & QR code management.
Integrate with and reutilize the backend of SDP for direct online payments to beneficiaries that own a phone.
Test smart contract minting & retrieval via Horizon API.
Perform unit tests for contract storage & ownership validation.
Deliverables: May 29th, 2025
NFT-based beneficiary systems live on Stellar Testnet.
Web interface for minting/testing NFTs.
QR codes linked to blockchain identities.
$25,000
Objective: Enable offline cash payments while recording transactions on chain.
Develop a smart contract to register payments against beneficiary NFTs.
Customize offline Billy app for payment agencies to download list of hashed Ids, scan QR codes, register beneficiary security pin code and record offline payments.
Offline QR payments are encrypted and stored in Billy App (mobile device). When Billy App has internet connectivity, the QR payments are uploaded to the Web App database in batches. Each batch request from Billy App will include the total number of payments and the list of the QR codes. Web API will only respond successfully when the list of transactions received match the total number of transactions in the request.
After successfully receiving the offline payments and storing them in the Web App database, the Web App relayer will connect to the smart contract to register the payments.
Test integration with Stellar Horizon API for transaction verification.
Conduct functional tests for payment recording & reconciliation.
Deliverables: June 30th, 2025
Payment tracking system deployed on Testnet.
Billy app can scan QR codes & register payments offline.
Web app shows payment history for each beneficiary.
$20,000
Objective: Connect all components & run end-to-end system tests.
Integrate mobile, web, and blockchain components.
Check for code quality and efficiency.
Implement security audits ensuring that dependencies are free of known vulnerabilities and use formal verification tools to check for no unauthorized access and that funds cannot be lost or misrouted.
Perform stress testing with high transaction loads.
Conduct UAT (User Acceptance Testing).
Deploy Soroban & Ethereum smart contracts to mainnet.
Deploy web & mobile apps to production.
Final security & performance review.
Deliverables: August 15th, 2025
Fully functional end-to-end system on Stellar
Web dashboard, Billy app, and blockchain integrations tested.
Security & compliance checks completed.
Fully operational system deployed on Stellar.
Live tracking of aid disbursements using blockchain.
$15,000
Coala Pay has been designed by aid workers looking to solve challenges they faced in delivering programs around the world. Our team members -17 of us- have worked in some of the world’s most challenging responses, from Afghanistan to, Darfur, to Myanmar, and have decades of experience in cash distribution, program design, impact evaluation, due diligence, and program management.
KCoala
No other submissions.