Accept stablecoins

Customers pay USDT or USDC straight into your own wallets. No processor holds the money and none takes a cut. The service watches the chains, recognises each payment, and settles the order through the same state machine as every other rail.

All EVM networks share one 0x wallet — the same address works on every one of them — and are watched straight from the chain (Transfer logs over public RPC, no API key). How far each has been read is kept in the database, so a restart resumes instead of missing blocks. A network's RPC can be overridden per network in the settings.

Prices can be in any currency. A stablecoin is a dollar, so a price in roubles, euros or tenge is converted when the invoice opens, and that rate is fixed for the invoice — see exchange rates.

How a payment is recognised

A USDT transfer on TRON or Ethereum carries a sender, a receiver and an amount — nothing else. There is no memo field to say which order it pays. So with one receiving wallet, the amount is the identifier:

Each invoice asks for the price plus a few millionths — under a cent — and keeps that amount to itself until it is paid or can no longer be. A partial unique index in the database guarantees no two open invoices ever share one, even when two checkouts race for the same price.

The checkout shows the amount with the identifying digits set apart, a copy button, a QR code (an EIP-681 / Solana Pay / ton:// link where the chain has a standard), a countdown, and a warning naming the network.

Set it up

In Admin → Crypto payments:

1. Wallets — paste a receiving address per network. Each is checked as an address on its own network (checksums included) before it is saved; a network left empty is not offered.
2. Chain access — No keys are needed; a TronGrid or Toncenter key raises their rate limits. Keys are stored write-only.
3. Turn on. The rail refuses to turn on with no network it can actually watch.

The page says per network whether it is accepting payments, and when the watcher last checked.

Exchange rates

A price in any currency other than USD is converted to dollars when the invoice opens:

9 000 RUB ÷ 90 RUB per $1 = $100   → + 2% markup = $102   → invoice asks for 102.000137 USDT

• Rates come from open.er-api.com (160+ currencies, daily), falling back to the Central Bank of Russia (the rouble, plus cross rates through it). They are stored and refreshed hourly.
• Pinned rates win over both — for a rate you set yourself, e.g. what USDT actually costs you in roubles rather than the official dollar rate.
• Markup (0–20 %, default 0) is added to converted prices only, never to a dollar price. It covers the gap between a reference rate and what dollars cost you, and movement while the invoice is open.
• The amount is rounded up to the token's smallest unit: the customer covers the last fraction, the shop is never short by it.
• The rate used, its source, the markup and the original price are recorded on the invoice and shown to the customer under the amount.
• A currency with no rate published in the last four days is not offered crypto at all, rather than charged at a stale rate.

Set the markup, pin rates and see the rate each of your currencies will be charged at in Admin → Crypto payments → Exchange rates.

The watcher

Every 30 seconds, for each network and token with an open invoice, the watcher asks that chain's public API for recent incoming transfers — TronGrid, Toncenter, Solana RPC and each EVM network's RPC. An idle shop makes no calls at all.

Each transfer is recorded once, idempotently, and:

• matches an open invoice → the invoice moves to confirming, then paid when final. Each step becomes an ordinary webhook event, so settlement goes through the same processor, reconciliation and state machine as Stripe or an app store.
• matches nothing → it is kept as an unmatched transfer for an admin, never dropped.

Before an intent is reported paid, the transfer is checked against its invoice: our wallet, the right chain and token, at least the invoiced amount.

Deadlines and late money

An invoice counts down (60 minutes by default). When the timer runs out the customer can get a new invoice — but a payment that arrives late is still credited for a grace period (24 hours by default), because the amount stays reserved. A blockchain transfer cannot be declined, so turning late money away would only move the problem to a support ticket.

After the grace period an unpaid invoice expires, and its order with it.

Switching network at checkout replaces the invoice — the old one's address and amount are wrong for what the customer is about to send — and gives its amount back. Once a transfer has been seen, the invoice cannot be replaced.

Unmatched transfers

Money that reached a wallet without matching an open invoice:

• the customer sent the round price instead of the exact amount;
• an exchange deducted a withdrawal fee and sent less;
• the payment arrived after the grace period;
• a second payment for an invoice already paid.

Admin → Crypto payments → Transfers lists them, each with the invoice it most likely was for. Check it on the explorer, then assign it — the order is settled as paid — or set it aside with a reason (refunded by hand, a test). An expired order cannot be settled this way: refund the customer or open a new order and assign the transfer to its invoice.

An external indexer (optional)

If you already run an indexer, it can report transfers to POST /webhooks/crypto with the shared secret in x-webhook-secret (set it on the settings page; without one the endpoint refuses everything):

{
  "chain": "TRON",
  "txHash": "903aad…",
  "from": "TDqS…",
  "to": "TNXo…",
  "token": "USDT",
  "amount": "100.000137",
  "confirmations": 19
}

amount is either a decimal in token units ("100.000137") or an integer in the token's smallest unit ("100000137"). Reports go through the same ledger as the watcher's, so both can run at once. A memo naming the invoice is honoured on chains that carry one.

Next

• Agents pay: x402 and the INITE wallet — AI agents pay a checkout in USDC on Base by themselves, through the same invoices and watcher.
• Go to production — providers, webhook URL, feature flags.
• Receive billing events — billing.payment.status_changed fires for crypto too.