MoonPay Trade Swidge Usage

Install the module, configure API access, select supported tokens, and preview a quote. This accountless flow does not submit a transaction. For support, see Need Help?.

Install the module

Use Node.js with global fetch and npm. Obtain a SwapsXYZ API key from your MoonPay integration contact. Keep it in secret-managed configuration and out of client bundles and logs.

Install the version covered by these pages:

npm install @moonpay/wdk-protocol-swidge-moonpay-trade@0.2.0

The module installs its core wallet dependency. You do not need a chain-specific wallet package for this accountless example. The execution guide installs the EVM wallet separately.

Configure API access

Create an ES module file such as quote.mjs. The snippets below belong in that file, in order.

Construct MoonPayTradeSwidgeProtocol with no wallet:

import MoonPayTradeSwidgeProtocol from '@moonpay/wdk-protocol-swidge-moonpay-trade'

const apiKey = process.env.SWAPS_XYZ_KEY
if (!apiKey) throw new Error('Set SWAPS_XYZ_KEY')

const protocol = new MoonPayTradeSwidgeProtocol(undefined, { apiKey })

Select supported tokens

This example uses Ethereum, chain id 1, and two token identifiers supplied by your application's approved token selection. Before quoting, verify each selected token's address and decimals against its issuer or protocol's deployment information.

1. Set MOONPAY_FROM_TOKEN_ID and MOONPAY_TO_TOKEN_ID to exact discovered identifiers in the form chainId:address.
2. Set MOONPAY_FROM_DECIMALS and MOONPAY_TO_DECIMALS to the precision verified from that deployment information.
3. Set MOONPAY_FROM_AMOUNT to a positive integer string in the source token's smallest unit.
4. Require both identifiers to remain in the current provider response. Do not resolve an asset by symbol alone.

Check the chain with getSupportedChains():

const chainId = 1
const chains = await protocol.getSupportedChains()
if (!chains.some(chain => Number(chain.id) === chainId)) {
  throw new Error('The provider does not currently list Ethereum')
}

Resolve the exact selected identifiers with getSupportedTokens():

const tokens = await protocol.getSupportedTokens({ fromChain: chainId })
const from = tokens.find(token => token.token === process.env.MOONPAY_FROM_TOKEN_ID)
const to = tokens.find(token => token.token === process.env.MOONPAY_TO_TOKEN_ID)
const amount = process.env.MOONPAY_FROM_AMOUNT ?? ''
const fromDecimals = Number(process.env.MOONPAY_FROM_DECIMALS)
const toDecimals = Number(process.env.MOONPAY_TO_DECIMALS)

if (!from || !to || from.token === to.token) {
  throw new Error('Select two different approved tokens from the provider response')
}
if (![fromDecimals, toDecimals].every(value => Number.isInteger(value) && value >= 0) ||
    from.decimals !== fromDecimals || to.decimals !== toDecimals) {
  throw new Error('Provider token precision differs from the verified token metadata')
}
if (!/^[1-9][0-9]*$/.test(amount)) {
  throw new Error('Set MOONPAY_FROM_AMOUNT to a positive integer in source token units')
}

const route = {
  fromToken: from.token,
  toToken: to.token,
  fromTokenAmount: BigInt(amount)
}

The embedded chain in each discovered identifier determines the route. For cross-chain operations, discover the destination token on its own chain and supply an explicitly validated destination recipient before execution. Do not assume the same address represents the same asset on another chain.

Preview a quote

Request an indicative quote with quoteSwidge():

const quote = await protocol.quoteSwidge(route)
console.log({
  input: quote.fromTokenAmount.toString(),
  expectedOutput: quote.toTokenAmount.toString(),
  minimumOutput: quote.toTokenAmountMin.toString()
})

Run the file after configuring the environment variables:

node quote.mjs

A successful call returns amounts as bigint values and itemized fees. Format each amount using its token's verified decimals. Keep fee amounts separate by token and chain; they are not interchangeable units. The accountless quote does not include the wallet's deposit-gas estimate.

The provider can reject a pair or amount even when both tokens appear in discovery. See errors for response handling.

Next Steps

Need Help?