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ProxxlyOffline-capable tap payments infrastructure
Payment infrastructure that turns two ordinary Android phones into a card and a card reader, so a tap works even where there's no network.
The problem
The reader nobody can afford
Every contactless payment system in Ghana needs special hardware most small merchants can't afford, while the NFC chip already in everyone's phone sits unused.
Connectivity is also least reliable exactly where small payments happen, trotro stops, market interiors, campus corners.
The solution
Two phones, one tap, no network
An Android SDK and REST API built on a multi-tenant, double-entry ledger. One phone emulates a contactless card; another reads it like a terminal. No special hardware on either side.
The tap completes entirely offline. The two phones authenticate each other cryptographically, and the payment settles later once a connection returns.
It's not a consumer wallet app; it's infrastructure other products (banks, transport operators, schools, apps) integrate with, the way a shopper never sees Paystack directly.
Proven on hardware
It works on real phones
In August 2026 the whole chain ran end to end on two ordinary mid-range Android handsets. Both enrolled with hardware-backed keys, verified at TEE level against genuine manufacturer attestation. Eight payments were tapped between them with no network involved, held on the terminal, and settled four days later, exactly once.
- 8 of 8 taps completed, with no failed or duplicated exchanges
- Settled exactly once after four days offline, across an app reinstall
- Payer debited and merchant credited to the exact pesewa, ledger reconciled with zero drift
- Hardware-backed keys on both handsets, verified at TEE level
- 292 automated tests, plus 10,000 concurrent ledger operations with zero drift
- The offline protocol is implemented twice, in TypeScript and Kotlin, locked to shared test vectors so the two can't silently drift
That run used test value in a development ledger. Proxxly remains pre-pilot: there is no live deployment, no customer, and no commercial transaction has been processed. It is designed for Ghana's regulatory environment, with a closed-loop-first approach.
Stack
How it's built
- Kotlin / Android
- Host Card Emulation
- NFC reader mode
- Hardware-backed Keystore
- TypeScript
- Fastify
- PostgreSQL
- ECDSA P-256
- AES-256-GCM
Contact
Let's build something.
Investors, city and transport people, partners, or someone who just wants to ask about the work. Email lands with me directly and I answer.
valiborntech@gmail.com