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Nelo lets a shopkeeper take a card-free payment on the Android phone they already own. The money settles in USDC on Solana, the merchant sees the amount in their own currency, and a licensed partner pays it into their own bank account. The part that matters is what happens when the network drops.
Offline mode is a prepaid balance, not a promise to pay. Before going offline, the payer locks funds into an on-chain vault. You cannot spend offline what you have not already locked — which disposes of both “what if they have no money” and “what if they don’t have enough” at once.

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The two facts this is built on

Neither is new. Nobody had put them together.

Solana verifies P-256

The secp256r1 precompile activated on mainnet in June 2025, so a program can verify a NIST P-256 signature on chain.

Android signs P-256

P-256 is the one curve uniformly supported by Android StrongBox, the phone’s secure element.
The secure element signs. The chain verifies. There is no trusted server anywhere in the value path — not Nelo’s, not anyone’s.

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What a sale looks like

1

The merchant types an amount

In their own currency, the way they always would. Nothing on screen says the word crypto.
2

The customer pays

A Solana Pay code, scannable by any wallet they already have. No Nelo app on the customer side.
3

The terminal confirms

It watches the chain and validates what actually arrived — right payee, right mint, enough money, transaction did not fail.
4

The takings land in the day-book

Grouped by the merchant’s own calendar day, not UTC’s.
5

Payout runs on a schedule

A licensed partner converts and disburses to their bank or mobile money. The merchant never off-ramps anything.
That last step is the decision that separates a POS from a crypto POS. Off-ramping is brutal if the merchant has to do it and invisible if the platform does it on a schedule. A merchant who must visit an exchange to get paid will not use this twice.

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Where to go next

Quickstart

Clone it, install it, run the test suite.

Architecture

Every moving part and how they fit.

The trust model

Why offline double-spend is closed, and what it costs.

Project status

What is built, what is proven, and what is neither.
This is a hackathon project in active development. Some of it is proven by tests that have actually run; some of it is written and unexecuted; some is a declared stub. Project status and Testing say exactly which is which, and those pages are kept honest rather than flattering. Do not put this near real money yet.