Supported stablecoins and currencies

Marlin supports USDC, PYUSD, and USDG on Solana mainnet and devnet. Learn how amounts work, what the currency field maps to, and how funds settle.

Marlin is a stablecoin-native billing platform. Rather than processing traditional fiat payments through a bank network, every transaction settles directly on Solana using one of three supported stablecoins. Because all three tokens share the same six-decimal precision, the same amount encoding rules apply across the board.

Supported tokens

Marlin supports USDC, PYUSD, and USDG on both Solana mainnet and devnet.

USDC

USD Coin — issued by Circle. The most widely used stablecoin on Solana.

PYUSD

PayPal USD — issued by PayPal. Regulated US dollar stablecoin.

USDG

Global Dollar — issued by the Global Dollar Network.

Mint addresses

Each token is identified by its SPL mint address on Solana:

Token	Network	Mint address
USDC	Mainnet	EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v
PYUSD	Mainnet	2b1kV6DkPAnxd5ixfnxCpjxmKwqjjaYmCZfHsFu24GXo
USDG	Mainnet	2u1tszSeqZ3qBWF3uNGPFc8TzMk2tdiwknnRMWGWjGWH
USDC	Devnet	4zMMC9srt5Ri5X14GAgXhaHii3GnPAEERYPJgZJDncDU
PYUSD	Devnet	CXk2AMBfi3TwaEL2468s6zP8xq9NxTXjp9gjMgzeUynM
USDG	Devnet	Gh9ZwEmdLJ8DscKNTkTqPbNwLNNBjuSzaG9Vp2KGtKJr

Marlin resolves the correct mint address automatically based on your account’s active network — you specify the currency by symbol ("USDC", "PYUSD", or "USDG") in your API requests.

How amounts work

All amounts in Marlin — on invoices, plans, and API responses — are expressed as integers in the token’s smallest unit, not as decimal strings. All three supported stablecoins use 6 decimal places.

Human-readable amount	amount value
$1.00	1000000
$9.90	9900000
$49.00	49000000
$0.01	10000

To convert: multiply the dollar amount by 10^6. To display a stored amount: divide by 10^6 and format to two decimal places.

Never use floating-point arithmetic for amount calculations. Use BigInt internally to avoid rounding errors. Multiply by 10n ** 6n to convert to the smallest unit, and divide to format for display.

// Convert a decimal string to the smallest unit
function toSmallestUnit(decimal: string, decimals = 6): bigint {
  const [whole, fraction = ""] = decimal.split(".");
  const padded = fraction.padEnd(decimals, "0").slice(0, decimals);
  return BigInt(whole) * BigInt(10 ** decimals) + BigInt(padded);
}

// toSmallestUnit("49.00") → 49000000n
// toSmallestUnit("9.90")  →  9900000n

The currency field

The currency field on an invoice or subscription plan is a string that maps to one of the supported token symbols: "USDC", "PYUSD", or "USDG". Marlin resolves this symbol to the correct mint address for the active cluster (mainnet or devnet) before constructing any on-chain transaction.

// Creating an invoice in PYUSD
await marlin.invoices.create({
  customerId: "cus_01HXYZ",
  currency: "PYUSD",
  lineItems: [{ description: "Consulting — May 2026", quantity: 1, unitAmount: 150000000 }],
  autoSend: true,
});

When you onboard as a merchant, you choose a default settlement mint for your account. All invoices and plans use this default unless you explicitly pass a currency field to override it on a per-invoice or per-plan basis.

Non-custodial settlement

Marlin never holds your funds. When a customer pays an invoice, the on-chain smart contract transfers tokens atomically in a single Solana transaction:

• 99.5% of the invoice amount goes directly to your configured settlement wallet.
• 0.5% (50 basis points) goes to the Marlin protocol treasury.

There is no withdrawal step, no daily payout batch, and no intermediary wallet. The moment the transaction confirms on-chain, the funds are in your wallet.

You can verify any payment independently using the transactionSignature on a paid invoice. Paste it into Solscan or any Solana explorer to see the exact token transfers.