Amounts

Amounts are decimal strings in the asset's own units: "49.90" USDT, "0.0015" BTC. They are never JSON numbers, so no amount is ever rounded by floating point on its way to you.

• What you send: at most as many decimal places as the asset has (GET /v1/assets lists each asset's decimals). A more precise amount is refused with amount_too_precise, not rounded.
• What comes back: the canonical form, with no trailing zeros: "49.90" comes back as "49.9", and zero as "0".
• Minimums: every asset has a minimum payment, so network fees can't eat it. GET /v1/assets and GET /v1/min-amount show them; a smaller amount is refused with amount_too_small.
• Prices in a currency (price_amount) are strings too, with at most two decimal places.

try {
  await nowgate.payments.create({ network: "tron", asset: "USDT", amount: "25.0000001" });
} catch (err) {
  if (!(err instanceof InvalidRequestError)) throw err;
  // err.code is "amount_too_precise"; each field's problem has its JSON pointer
  pointer = err.errors[0]?.pointer;
  assert.equal(err.code, "amount_too_precise");
}

try:
    client.payments.create(network="tron", asset="USDT", amount="25.0000001")
except InvalidRequestError as err:
    # err.code is "amount_too_precise"; each field's problem has its JSON pointer
    pointer = err.errors[0]["pointer"]
    check(err.code == "amount_too_precise", err.code)

try {
    $nowgate->payments->create(['network' => 'tron', 'asset' => 'USDT', 'amount' => '25.0000001']);
} catch (InvalidRequestException $e) {
    // $e->errorCode is 'amount_too_precise'; each field's problem has its JSON pointer
    $pointer = $e->errors[0]['pointer'] ?? null;
    check($e->errorCode === 'amount_too_precise', $e->errorCode);
}

In the SDKs#

The SDKs check that an amount is a string before sending, and leave its format to the API, so every client gets the same answer with the field's pointer.

Converting#

Each SDK has exact helpers, without floating point, for an asset's smallest units (its decimals from assets.list()):