StableFX

Tutorial: Test your StableFX Integration as a Maker

This tutorial walks you through the steps to test your StableFX integration as a maker.

Before you begin, ensure that you have:

  • Obtained a sandbox API key for StableFX from Circle
  • Obtained testnet USDC in a supported wallet on Arc
  • installed cURL on your development machine

This guide provides API requests in cURL format, along with example responses.

Query for trades with the confirmed status using the get all trades endpoint. The following is an example request:

Shell
curl --request GET \
  --url https://api-sandbox.circle.com/v1/exchange/stablefx/trades?type=maker&status=confirmed \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer ${YOUR_API_KEY}' \

Response

JSON
{
  "data": [
    {
      "id": "c2558cd1-98b5-4ccd-90b8-96891512af20",
      "contractTradeId": 42,
      "status": "confirmed",
      "rate": 0.915,
      "from": {
        "currency": "USDC",
        "amount": "10"
      },
      "to": {
        "currency": "EURC",
        "amount": "9.15"
      },
      "createDate": "2023-01-01T12:04:05Z",
      "updateDate": "2023-01-01T12:04:05Z",
      "quoteId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5"
    }
  ],
  "pagination": {
    "next": "",
    "previous": ""
  }
}

Decide which trades to take from the maker side, and register your signature for those trades.

Using the id field from the response in the previous step, get the typed data for the trade using the generate trade presign data endpoint. The following is an example request:

Shell
curl --request GET \
  --url https://api-sandbox.circle.com/v1/exchange/stablefx/signatures/presign/maker/c2558cd1-98b5-4ccd-90b8-96891512af20 \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer ${YOUR_API_KEY}'

Response

JSON
{
  "consideration": {
    "quoteId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5",
    "base": "0x...",
    "quote": "0x...",
    "baseAmount": "10",
    "quoteAmount": "9.15",
    "maturity": 1752148800
  },
  "deadline": 1752149700,
  "fee": "100000"
}

Using your wallet, sign the typed data returned from the previous step.

Submit the signed data to the submit a trade signature endpoint. The following is an example request for the signed data:

Shell

curl --request POST \
  --url https://api-sandbox.circle.com/v1/exchange/stablefx/signatures \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer ${YOUR_API_KEY}' \
  --header 'Content-Type: application/json' \
  --data '
{
  "tradeId": "c2558cd1-98b5-4ccd-90b8-96891512af20",
  "type": "maker",
  "address": "0xabc123...",
  "details": {
    "consideration": {
      "quoteId": "c4d1da72-111e-4d52-bdbf-2e74a2d803d5",
      "base": "0x...",
      "quote": "0x...",
      "baseAmount": "10",
      "quoteAmount": "9.15",
      "maturity": 1752148800
    },
    "deadline": 1752149700,
    "fee": "100000"
  },
  "signature": "0xsignature"
}
'

Use the following steps to fund the trade onchain.

Before you send funds onchain, you should confirm that the trade is ready for funding. To do this, call the get all trades endpoint. You should filter the response by the taker_funded status.

To use the StableFX API to deliver the funds onchain, you must first sign the funding typed data with an EIP-712 signature. To get the data to sign, call the generate funding presign data endpoint. Your request must include the contract ID of the trade and the side of the trade that you are taking. The following an example request:

Shell
curl --request POST \
  --url https://api-sandbox.circle.com/v1/exchange/stablefx/signatures/funding/presign \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer ${YOUR_API_KEY}' \
  --header 'Content-Type: application/json' \
  --data '
  {
  "contractTradeIds": ["${stablefx_contract_trade_id}"],
  "type": "maker"
}
'

Response

JSON
{
  "typedData": {
    "domain": {
      "name": "Permit2",
      "chainId": 11155111,
      "verifyingContract": "0xffd21ca8F0876DaFAD7de09404E0c1f868bbf1AE"
    },
    "types": {
      "EIP712Domain": [
        {
          "name": "name",
          "type": "string"
        },

        {
          "name": "chainId",
          "type": "uint256"
        },

        {
          "name": "verifyingContract",
          "type": "address"
        }
      ],
      "TokenPermissions": [
        {
          "name": "token",
          "type": "address"
        },

        {
          "name": "amount",
          "type": "uint256"
        }
      ],
      "SingleTradeWitness": [
        {
          "name": "id",
          "type": "uint256"
        }
      ],
      "PermitWitnessTransferFrom": [
        {
          "name": "permitted",
          "type": "TokenPermissions"
        },

        {
          "name": "spender",
          "type": "address"
        },

        {
          "name": "nonce",
          "type": "uint256"
        },

        {
          "name": "deadline",
          "type": "uint256"
        },

        {
          "name": "witness",
          "type": "SingleTradeWitness"
        }
      ]
    },
    "primaryType": "PermitWitnessTransferFrom",
    "message": {
      "permitted": {
        "token": "0xTOKEN",
        "amount": "1000"
      },
      "spender": "0xffd21ca8F0876DaFAD7de09404E0c1f868bbf1AE",
      "nonce": "42",
      "deadline": "1735689600",
      "witness": {
        "id": "10"
      }
    }
  }
}

The StableFX API can handle the onchain transaction for you through the fund trades endpoint. You must submit the maker-specific funding data along with your signature.

Shell
curl --request POST \
  --url https://api-sandbox.circle.com/v1/exchange/stablefx/fund \
  --header 'Accept: application/json' \
  --header 'Authorization: Bearer ${YOUR_API_KEY}' \
  --header 'Content-Type: application/json' \
  --data '
{
  "type": "maker",
  "signature": "0xsignature",
  "permit2": {
    "permitted": {
      "token": "0xTOKEN1",
      "amount": "9.15"
    },
    "spender": "0xTOKEN1",
    "nonce": "123456",
    "deadline": 1752149700,
    "witness": {
      "id": "123456"
    }
  }
}
'

If the signed data is accepted, the API returns a blank 200 response.

Note that the sandbox query for trades endpoint returns multiple trades. This can be useful for testing a batch integration. If you are testing batching, you need to get the contractTradeId for each trade that you'd like to fund. You should complete part 2 for each trade that you'd like to fund.

Once you have the array of IDs, and your signature is submitted for each trade, you can use the same fund trades endpoint to fund multiple trades by submitting the permit2 data for each trade along with the appropriate signatures.

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