Lóng Protocol turns a crypto payment on any rail into a proof of payment that anyone can check. The money moves natively, wallet to wallet. Only the proof is written on chain: recorded on Solana, anchored on Ethereum. No custody, no token to buy, no fee on the sale.
Illustrative register feed. Solana sees a commitment, a merchant id, the rail, which verifiers agreed and when. Ethereum sees one Merkle root per epoch.
A transaction hash says that coins moved. It says nothing about what was bought, who received it, or whether the seller accepted it. Lóng Protocol adds the missing half and keeps the details with the two people who were there.
Independent verifiers confirm the transfer, the merchant signs the receipt, and a commitment is recorded on Solana. Each epoch of records is anchored on Ethereum.
By default only a hash goes public. Amount, items and parties stay encrypted with the payer and the merchant. Show one field to one person when you need to.
Any rail in, one register out. Wallets, point-of-sale apps and venues speak LPR-1, one request format for every coin LongPay accepts, so a proof means the same thing everywhere.
Watch one HK$42 coffee, paid in USDT on Tron at a counter in Sheung Wan, become a proof. The customer pays the way they always do. Pause the sandbox or jump to any step.
They scan the LPR-1 request and send the exact amount from any wallet: Lightning, on-chain Bitcoin, or USDT and USDC on Tron, Ethereum or Polygon. The funds go straight to the merchant's own address. Lóng never touches the money.
On Tron, the LongPay detector checks the official token contract, the address, the amount within tolerance and the confirmations. An independent oracle reading its own Tron node must agree. Each rail has its own verifier set and threshold.
The receipt is hashed into one commitment. The merchant's receipt key, already inside the LongPay app, signs it during the normal checkout. A payer using LongPay Wallet, or any LPR-1 wallet, can add their own signature. Now both sides have said so.
Solana stores the commitment, the merchant id, the rail, which verifiers agreed and when. The record is confirmed once the threshold is met, and Pearls are earned. At the end of the epoch, the Merkle root of all records is anchored on Ethereum.
| Rail | How the register learns the payment happened | At launch | Later |
|---|---|---|---|
| Lightning | The invoice preimage is the proof itself. | 1 of 1 | Same |
| Tron · USDT, USDC | LongPay detector plus an independent oracle reading a Tron node. | 2 of 2 | 2 of 3 with a third verifier |
| Ethereum · Polygon | Detector plus independent oracle, as on Tron. | 2 of 2 | Guardian-signed cross-chain queries |
| Bitcoin on-chain | Detector plus independent oracle, as on Tron. | 2 of 2 | SPV proof against a header relay |
Two chains, two jobs. Solana records every proof as it happens, cheaply enough that a HK$42 coffee is worth recording. Ethereum holds the Merkle root of each epoch, so any proof can be checked on the most widely trusted settlement layer by anyone with a node.
A coffee, a taxi, a bar tab. Recording each one needs sub-second finality and a cost close to zero. Solana gives both.
Accountants, banks and counterparties know how to read an Ethereum contract. Each epoch root is signed by a threshold of anchor signers, at least one of them outside LongPay, and stays there permanently.
Given a commitment, anyone can fetch its Merkle path from the register and check it against the root on Ethereum with a few lines of code.
Sample data. The live verifier will accept any commitment from the register.
Check full proofs in the explorer demo| What it proves | Screenshot | Transaction hash | Lóng proof of payment |
|---|---|---|---|
| Coins moved | No | Yes | Yes · verified per rail |
| The seller accepted the sale | No | No | Yes · merchant signature |
| What was sold | Claimed | No | Yes · disclosed on demand |
| A third party can check it | No | Only the transfer | Yes · on Solana and Ethereum |
| Payer stays private | Depends | Address exposed | Yes · not recorded |
| Works across chains | Manual | One chain | Yes · one format, every rail |
Each shop and each sale chooses. Public records feed network stats and a verified-venue badge. Private records show nothing but the commitment and can disclose a single field on demand.
Try it: tap Disclose on one field of the receipt.
On chain: commitment, merchant id, rail, verifier bitmap and time. Hidden fields can be proven one at a time.
The register is deliberately small. It cannot leak what it never stores.
A hash of the full receipt. One changed character in the receipt changes it.
A registry id, not a wallet address. The shop can rotate keys without changing identity.
Which chain the money moved on, so the right threshold applies.
Which verifiers agreed. Anyone can check that the rail's threshold was met.
Confirmed at threshold. A refund or correction is a new record that supersedes the old one, never an edit.
When the threshold was reached, from the Solana clock.
One line per epoch in the PoPAnchor contract. Every proof in the epoch can be checked from Ethereum alone, with its Merkle path.
Amount and items appear only if the venue publishes that record. A payer who acknowledges a receipt adds their own Solana key, by choice.
Lóng Protocol is the layer underneath products people already use. Each one is a way into the network.
Point of sale for merchants. Charge in Bitcoin, USDT or USDC, settle to your own wallet, and every sale produces a proof.
A self-custodial wallet that speaks LPR-1. Pay any Lóng request, acknowledge receipts and keep your private proofs in your pocket.
Learn Bitcoin and crypto payments from zero, in English, Chinese or French, with an AI tutor you can ask anything. Finished lessons earn Pearls.
One request format, a verifier set you can join, and a register you can read on Solana and check on Ethereum. Build on proofs instead of screenshots.
Confirmed proofs and finished lessons earn Pearls. They are loyalty points, not a token you can trade: they live only in approved accounts, cannot be sent to anyone, and are spent as discounts. Partners can issue their own points under the same rules.
We never take a percentage of a transaction. Plans are flat and monthly, so a busy night costs the same as a quiet one.
Funds go wallet to wallet on the native chain. Lóng records proofs. It never holds, routes or converts a payment.
No protocol token and no staking. Pearls are points. The apps pay the fee for writing a proof, not the people paying.
LPR-1 is the request format every Lóng wallet and point of sale understands. One object says what is owed, which rails are accepted and where the proof goes.
The contracts are written and tested but not yet audited or deployed. This is the order the network goes live in.
Register and Pearls programs on Solana, PoPAnchor and a Pearls reference on Ethereum. End-to-end tests pass.
Every sale gets a receipt and a merchant signature inside the app, before anything touches a chain.
LongPay writes real proofs to devnet. The program is audited before mainnet.
Pearls move from the LongPay database to the closed-loop program, after legal sign-off.
An oracle outside LongPay joins every rail, and Ethereum anchoring starts with an outside signer.
A public register to look up any proof, and per-field disclosure for payers and merchants.
Preview the demoMerchants already on LongPay get proofs first. Wallets, venues and developers can join the verifier set and the SDK programme, from Hong Kong outward.