Case study
What makes this project compelling is that it solves a real local payment edge case with a complete service model. The repo shows a wallet-connected checkout flow, a TypeScript backend for quote generation and bill delivery, and an admin-operated float system that turns crypto receipts into usable NGN service fulfillment.
Project snapshot
3
coordinated layers: web app, TypeScript backend, and smart-contract workspace
32
backend source files handling pricing, verification, transactions, float, admin, and notifications
90s
quote lifetime designed into the pricing flow to keep crypto-fiat settlement bounded
6+
utility categories supported across airtime, data, power, cable, education, and insurance
What NEXGEN built
Crypto quote engine that converts NGN bill amounts into time-bound USDT payment requests with service context preserved end to end.
On-chain verification layer on Polygon that checks asset, recipient wallet, transfer value, transaction status, and anti-replay conditions before fulfillment.
Utility fulfillment system wired to VTPass for airtime, data, electricity, cable, education, and insurance service delivery.
Operational float management model for tracking NGN reserves, ledger movements, low-balance alerts, and delivery risk inside a bootstrapped service.
Merchant and admin surfaces for transaction history, white-label payment entry points, live sales tracking, and intervention tooling.
Why the project matters
Many fintech demos abstract away how money movement actually works. This repo shows the constraints, checks, and fallback thinking that make the product feel materially closer to a runnable service.
Built around a real liquidity constraint
CryptoBills is not pretending crypto instantly becomes fiat by magic. The product story explicitly includes a managed NGN float, payout thresholds, exposure limits, and top-up workflows, which makes the operating model much more credible.
Verification before fulfillment
The payment flow is designed around verification on demand instead of vague wallet screenshots or trust-based confirmation. The backend checks chain-level transfer evidence before it attempts bill delivery.
Utility-first rather than exchange-first
This is not a trading product wearing a payments label. The repo is organized around practical service delivery: categories, plan variations, beneficiary validation, receipts, and fast repeat usage.
Operations are part of the product
Admin metrics, low-float alerts, ledger visibility, and remote reconciliation are treated as first-class capabilities. That turns the build into a service operation system, not just a public checkout flow.
Architecture
Technology stack
What stands out
The combination of wallet UX, quote expiry, chain verification, and float operations gives CryptoBills a more defensible product story than a simple checkout page connected to a wallet button.
System breakdown
Quote and pricing engine
Rates are fetched and cached, service fees are computed using the documented hybrid model, and quotes are persisted with bill metadata so later verification and fulfillment can reconcile against the original user intent.
Blockchain verification flow
The backend verifies transaction hashes against the configured USDT contract and treasury wallet, parses transfer logs, applies a small amount tolerance, and prevents duplicate processing before moving the order state forward.
Service fulfillment and validation
VTPass integration is paired with live variation fetching and beneficiary checks so the frontend can validate meters, smartcards, or plan choices before any payment is requested.
Operational admin hub
The admin system tracks sales volume, success rate, transaction counts, float ledger events, and alert conditions, with API-key style protection and SES-powered notifications for low-balance or system-health events.
Repo evidence