Quickstart: Crypto Deposits

USDC is a “stablecoin,” a cryptocurrency that provides a stable level of purchasing power. As such, it is a popular currency for online transactions, and your customers will want to use it as a payment medium. This guide will walk you through the basics of accepting USDC on your site. Here we use the Ethereum blockchain as an example, but the same steps apply to other currencies and chains as well.

Steps:

1. Set up payment intent to pay with Crypto
2. Acquire blockchain address customer will pay to
3. Customer pays
4. Receive payment

1. Pay with Crypto

Once the customer reaches checkout and confirms they would like to pay with USDC on Ethereum, your system will send Circle a request to create a payment intent. Within this payment intent request you will specify the amount, currency, settlement currency, and chain.

Create a payment intent:

cURL

curl --location --request POST 'https://api-sandbox.circle.com/v1/paymentIntents' \
--header 'X-Requested-Id: ${GUID}' \
--header 'Authorization: Bearer ${YOUR_API_KEY}' \
--header 'Content-Type: application/json' \
--data-raw '{
 "idempotencyKey": "17607606-e383-4874-87c3-7e46a5dc03dd",
 "amount": {
   "amount": "1.00",
   "currency": "USD"
 },
 "settlementCurrency": "USD",
 "paymentMethods": [
   {
     "type": "blockchain",
     "chain": "ETH"
   }
 ]
}'

/**
 * See installation instructions at
 * https://developers.circle.com/circle-mint/circle-sdks
 */
import { Circle, CircleEnvironments, PaymentIntentCreationRequest } from "@circle-fin/circle-sdk";
import crypto from 'crypto';

const circle = new Circle(
    '<your-api-key>',
    CircleEnvironments.sandbox      // API base url
);

async function createCryptoPayment() {
    const reqBody: PaymentIntentCreationRequest = {
        amount: {
            amount: "1.00",
            currency: "USD"
        },
        settlementCurrency: "USD",
        paymentMethods: [
            {
                type: "blockchain",
                chain: "ETH"
            }
        ],
        idempotencyKey: crypto.randomUUID()
    };
    const resp = await circle.cryptoPaymentIntents.createPaymentIntent(reqBody);
    console.log(resp.data);
}
createCryptoPayment();

Response

{
  "data": {
    "id": "6e4d4047-db14-4c09-b238-1215aee50d03",
    "amount": {
      "amount": "1.00",
      "currency": "USD"
    },
    "amountPaid": {
      "amount": "0.00",
      "currency": "USD"
    },
    "amountRefunded": {
      "amount": "0.00",
      "currency": "USD"
    },
    "settlementCurrency": "USD",
    "paymentMethods": [
      {
        "type": "blockchain",
        "chain": "ETH"
      }
    ],
    "paymentIds": [],
    "timeline": [
      {
        "status": "created",
        "time": "2022-07-21T20:13:35.579331Z"
      }
    ],
    "createDate": "2022-07-21T20:13:35.578678Z",
    "updateDate": "2022-07-21T20:19:24.859052Z"
  }
}

Webhook notification

{
  "clientId": "f1397191-56e6-42fd-be86-0a7b9bd91522",
  "notificationType": "paymentIntents",
  "version": 1,
  "customAttributes": { "clientId": "f1397191-56e6-42fd-be86-0a7b9bd91522" },
  "paymentIntent": {
    "id": "6e4d4047-db14-4c09-b238-1215aee50d03",
    "amount": { "amount": "1.00", "currency": "USD" },
    "amountPaid": { "amount": "0.00", "currency": "USD" },
    "amountRefunded": { "amount": "0.00", "currency": "USD" },
    "settlementCurrency": "USD",
    "paymentMethods": [{ "type": "blockchain", "chain": "ETH" }],
    "paymentIds": [],
    "refundIds": [],
    "timeline": [
      { "status": "created", "time": "2022-07-21T20:13:35.579331Z" }
    ],
    "createDate": "2022-07-21T20:13:35.578678Z",
    "updateDate": "2022-07-21T20:13:35.578678Z"
  }
}

2. Acquire blockchain address customer will pay to

For security reasons, we do not synchronously return the deposit blockchain address. To retrieve the blockchain deposit address, you have two options:

1. Subscribe to webhook notifications
2. Poll Circle APIs

Option 1: Webhook Notification

To receive webhook notifications, follow the steps in the notifications quickstart. After you subscribe to notifications, you will receive updates for the payment intent whenever the resource is updated. In this case, when the paymentMethods.address is set, a notification is sent with a new timeline object with a status of pending.

Payment intent webhook notification

{
  "clientId": "f1397191-56e6-42fd-be86-0a7b9bd91522",
  "notificationType": "paymentIntents",
  "version": 1,
  "customAttributes": { "clientId": "f1397191-56e6-42fd-be86-0a7b9bd91522" },
  "paymentIntent": {
    "id": "6e4d4047-db14-4c09-b238-1215aee50d03",
    "amount": { "amount": "1.00", "currency": "USD" },
    "amountPaid": { "amount": "0.00", "currency": "USD" },
    "amountRefunded": { "amount": "0.00", "currency": "USD" },
    "settlementCurrency": "USD",
    "paymentMethods": [
      {
        "type": "blockchain",
        "chain": "ETH",
        "address": "0x97de855690955e0da79ce5c1b6804847e7070c7f"
      }
    ],
    "fees": [
      { "type": "blockchainLeaseFee", "amount": "0.00", "currency": "USD" }
    ],
    "paymentIds": [],
    "refundIds": [],
    "timeline": [
      { "status": "pending", "time": "2022-07-21T20:13:38.188286Z" },
      { "status": "created", "time": "2022-07-21T20:13:35.579331Z" }
    ],
    "createDate": "2022-07-21T20:13:35.578678Z",
    "updateDate": "2022-07-21T20:13:38.186831Z",
    "expiresOn": "2022-07-21T21:13:38.087275Z"
  }
}

Option 2: Poll Payment Intent Endpoint

If you prefer to poll get a payment intent, you can send get request until you receivepaymentMethods.address.

Retrieve payment intent:

cURL

curl --location --request GET 'https://api-sandbox.circle.com/v1/paymentIntents/{id}' \
--header 'X-Requested-Id: ${GUID}' \
--header 'Authorization: Bearer ${YOUR_API_KEY}'

/**
 * See installation instructions at
 * https://developers.circle.com/circle-mint/circle-sdks
 */
import { Circle, CircleEnvironments } from "@circle-fin/circle-sdk";

const circle = new Circle(
    '<your-api-key>',
    CircleEnvironments.sandbox      // API base url
);


// Create promise that gets resolved in time milliseconds
function delay(time: number) {
    return new Promise((resolve) => setTimeout(resolve, time));
}

async function getPaymentIntent(paymentInentId: string) {
    const resp = await circle.cryptoPaymentIntents.getPaymentIntent(paymentInentId);

    return resp.data;
}

async function pollPaymentIntent() {
    const paymentInentId = 'payment-intent-id';
    const pollInterval = 500;       // Interval (in ms) by which to poll

    let resp = undefined;
    while (true) {
        resp = await getPaymentIntent(paymentInentId);
        let depositAddress = resp.data?.paymentMethods[0].address;

        if (depositAddress) break;
        await delay(pollInterval);
    }
    console.log(resp);
}
pollPaymentIntent();

Response

{
  "data": {
    "id": "6e4d4047-db14-4c09-b238-1215aee50d03",
    "amount": {
      "amount": "1.00",
      "currency": "USD"
    },
    "amountPaid": {
      "amount": "0.00",
      "currency": "USD"
    },
    "amountRefunded": {
      "amount": "0.00",
      "currency": "USD"
    },
    "settlementCurrency": "USD",
    "paymentMethods": [
      {
        "type": "blockchain",
        "chain": "ETH",
        "address": "0x97de855690955e0da79ce5c1b6804847e7070c7f"
      }
    ],
    "fees": [
      { "type": "blockchainLeaseFee", "amount": "0.00", "currency": "USD" }
    ],
    "paymentIds": [],
    "refundIds": [],
    "timeline": [
      { "status": "pending", "time": "2022-07-21T20:13:38.188286Z" },
      { "status": "created", "time": "2022-07-21T20:13:35.579331Z" }
    ],
    "createDate": "2022-07-21T20:13:35.578678Z",
    "updateDate": "2022-07-21T20:13:38.186831Z",
    "expiresOn": "2022-07-21T21:13:38.087275Z"
  }
}

3. Enable customer payment

Once you receive the deposit address via paymentMethods.address, you’ll provide it to the customer along with the amount and currency to be paid. You can present the address two ways:

1. as plain text the customer can cut and paste; or
2. as a QR code the customer can scan via an app.

The customer then sends payment from their wallet (custodial or non-custodial).

When using transient payment intents, you can specify the timeframe in which the customer must send payment by adjusting the expiresOn setting.

4. Receive payment from Circle

Once Circle obtains payment on-chain, we create a Payment resource linked to the Payment Intent created earlier and update the status of that Payment Intent. Your firm will then receive payment via the method specified.

Option 1: Webhook Notifications

Payment intent webhook notification

{
  "clientId": "f1397191-56e6-42fd-be86-0a7b9bd91522",
  "notificationType": "paymentIntents",
  "version": 1,
  "customAttributes": { "clientId": "f1397191-56e6-42fd-be86-0a7b9bd91522" },
  "paymentIntent": {
    "id": "6e4d4047-db14-4c09-b238-1215aee50d03",
    "amount": { "amount": "1.00", "currency": "USD" },
    "amountPaid": { "amount": "1.00", "currency": "USD" },
    "amountRefunded": { "amount": "0.00", "currency": "USD" },
    "settlementCurrency": "USD",
    "paymentMethods": [
      {
        "type": "blockchain",
        "chain": "ETH",
        "address": "0x97de855690955e0da79ce5c1b6804847e7070c7f"
      }
    ],
    "fees": [
      { "type": "blockchainLeaseFee", "amount": "0.00", "currency": "USD" },
      { "type": "totalPaymentFees", "amount": "0.01", "currency": "USD" }
    ],
    "paymentIds": ["66c56b6a-fc79-338b-8b94-aacc4f0f18de"],
    "refundIds": [],
    "timeline": [
      {
        "status": "complete",
        "context": "paid",
        "time": "2022-07-21T20:19:24.861094Z"
      },
      { "status": "pending", "time": "2022-07-21T20:13:38.188286Z" },
      { "status": "created", "time": "2022-07-21T20:13:35.579331Z" }
    ],
    "createDate": "2022-07-21T20:13:35.578678Z",
    "updateDate": "2022-07-21T20:19:24.859052Z",
    "expiresOn": "2022-07-21T21:13:38.087275Z"
  }
}

Payment webhook notification

{
  "clientId": "f1397191-56e6-42fd-be86-0a7b9bd91522",
  "notificationType": "payments",
  "version": 1,
  "customAttributes": { "clientId": "f1397191-56e6-42fd-be86-0a7b9bd91522" },
  "payment": {
    "id": "66c56b6a-fc79-338b-8b94-aacc4f0f18de",
    "type": "payment",
    "status": "paid",
    "amount": { "amount": "1.00", "currency": "USD" },
    "fees": { "amount": "0.01", "currency": "USD" },
    "createDate": "2022-07-21T20:16:35.092Z",
    "updateDate": "2022-07-21T20:19:24.719Z",
    "merchantId": "f1397191-56e6-42fd-be86-0a7b9bd91522",
    "merchantWalletId": "1000999922",
    "paymentIntentId": "6e4d4047-db14-4c09-b238-1215aee50d03",
    "settlementAmount": { "amount": "1.00", "currency": "USD" },
    "fromAddresses": {
      "chain": "ETH",
      "addresses": ["0x0d4344cff68f72a5b9abded37ca5862941a62050"]
    },
    "depositAddress": {
      "chain": "ETH",
      "address": "0x97de855690955e0da79ce5c1b6804847e7070c7f"
    },
    "transactionHash": "0x7351585460bd657f320b9afa02a52c26d89272d0d10cc29913eb8b28e64fd906"
  }
}

Option 2: Retrieve Payment Intent and Payment

Retrieve a payment intent:

cURL

curl --location --request GET 'https://api-sandbox.circle.com/v1/paymentIntents/{id}' \
--header 'X-Requested-Id: ${GUID}' \
--header 'Authorization: Bearer ${YOUR_API_KEY}'

/**
 * See installation instructions at
 * https://developers.circle.com/circle-mint/circle-sdks
 */
import { Circle, CircleEnvironments } from '@circle-fin/circle-sdk'

const circle = new Circle(
  '<your-api-key>',
  CircleEnvironments.sandbox, // API base url
)

async function getPaymentIntent() {
  const paymentIntentId = '<payment-intent-id>'
  const resp =
    await circle.cryptoPaymentIntents.getPaymentIntent(paymentIntentId)

  console.log(resp.data)
}
getPaymentIntent()

Response

{
  "data": {
    "id": "6e4d4047-db14-4c09-b238-1215aee50d03",
    "amount": {
      "amount": "1.00",
      "currency": "USD"
    },
    "amountPaid": {
      "amount": "1.00",
      "currency": "USD"
    },
    "amountRefunded": {
      "amount": "0.00",
      "currency": "USD"
    },
    "settlementCurrency": "USD",
    "paymentMethods": [
      {
        "type": "blockchain",
        "chain": "ETH",
        "address": "0x97de855690955e0da79ce5c1b6804847e7070c7f"
      }
    ],
    "fees": [
      {
        "type": "blockchainLeaseFee",
        "amount": "0.00",
        "currency": "USD"
      },
      {
        "type": "totalPaymentFees",
        "amount": "0.01",
        "currency": "USD"
      }
    ],
    "paymentIds": ["66c56b6a-fc79-338b-8b94-aacc4f0f18de"],
    "refundIds": [],
    "timeline": [
      {
        "status": "complete",
        "context": "paid",
        "time": "2022-07-21T20:19:24.861094Z"
      },
      {
        "status": "pending",
        "time": "2022-07-21T20:13:38.188286Z"
      },
      {
        "status": "created",
        "time": "2022-07-21T20:13:35.579331Z"
      }
    ],
    "createDate": "2022-07-21T20:13:35.578678Z",
    "updateDate": "2022-07-21T20:19:24.859052Z",
    "expiresOn": "2022-07-21T21:13:38.087275Z"
  }
}

Retrieve a payment:

cURL

curl --location --request GET 'https://api-sandbox.circle.com/v1/payments/{id}' \
--header 'X-Requested-Id: ${GUID}' \
--header 'Authorization: Bearer ${YOUR_API_KEY}'

/**
 * See installation instructions at
 * https://developers.circle.com/circle-mint/circle-sdks
 */
import { Circle, CircleEnvironments } from '@circle-fin/circle-sdk'

const circle = new Circle(
  '<your-api-key>',
  CircleEnvironments.sandbox, // API base url
)

async function getPayment() {
  const paymentId = '<payment-id>'
  const resp = await circle.payments.getPayment(paymentId)

  console.log(resp.data)
}
getPayment()

Response

{
  "data": {
    "id": "66c56b6a-fc79-338b-8b94-aacc4f0f18de",
    "type": "payment",
    "status": "paid",
    "amount": {
      "amount": "1.00",
      "currency": "USD"
    },
    "fees": {
      "amount": "0.01",
      "currency": "USD"
    },
    "createDate": "2022-07-21T20:16:35.092852Z",
    "updateDate": "2022-07-21T20:19:24.719313Z",
    "merchantId": "f1397191-56e6-42fd-be86-0a7b9bd91522",
    "merchantWalletId": "1000999922",
    "paymentIntentId": "6e4d4047-db14-4c09-b238-1215aee50d03",
    "settlementAmount": {
      "amount": "1.00",
      "currency": "USD"
    },
    "fromAddresses": {
      "chain": "ETH",
      "addresses": ["0x0d4344cff68f72a5b9abded37ca5862941a62050"]
    },
    "depositAddress": {
      "chain": "ETH",
      "address": "0x97de855690955e0da79ce5c1b6804847e7070c7f"
    },
    "transactionHash": "0x7351585460bd657f320b9afa02a52c26d89272d0d10cc29913eb8b28e64fd906"
  }
}

For blockchains that require a ‘memo’ or ‘address tag’ (XLM, HBAR, etc.), the optional addressTag field will be present in the depositAddress object.

1. Get a Typed Message for Signing

Call the GET /payment/presign endpoint to fetch the typed message. The two required parameters are paymentIntentId , which can be retrieved from the GET /paymentIntent response or webhook notification; and endUserAddress which is the consumer wallet address.

Curl

curl --location 'https://api-sandbox.circle.com/v1/payments/presign?paymentIntentId=6e4d4047-db14-4c09-b238-1215aee50d03&endUserAddress=0x8381470ED67C3802402dbbFa0058E8871F017A6F' \
--header 'X-Requested-Id: ${GUID}' \
--header 'Authorization: Bearer ${YOUR_API_KEY}'

Response

{
  "data": {
    "typedData": {
      "domain": {
        "name": "USD Coin",
        "verifyingContract": "0x07865c6e87b9f70255377e024ace6630c1eaa37f",
        "version": "2",
        "chainId": 5
      },
      "message": {
        "from": "0x8381470ED67C3802402dbbFa0058E8871F017A6F",
        "to": "0xdB055877e6c13b6A6B25aBcAA29B393777dD0a73",
        "value": "5003456",
        "validAfter": 1675317371,
        "validBefore": 1675107967,
        "nonce": "0x4f716a578b96592599c3ca7b2a46453df87511d4809f608cec982d6e83632604"
      },
      "totalAmount": {
        "amount": "3.14",
        "currency": "USD"
      },
      "feeChargeModel": "endUser",
      "networkFeeQuote": {
        "quoteId": "5d0bb4e7-bd83-44dd-b8f5-53ddd5f35a3a",
        "amount": {
          "amount": "3.14",
          "currency": "USD"
        },
        "expiresAt": "2023-02-02T06:01:21.152737680Z"
      },
      "types": {
        "EIP712Domain": [
          {
            "name": "name",
            "type": "string"
          },
          {
            "name": "version",
            "type": "string"
          },
          {
            "name": "chainId",
            "type": "uint256"
          },
          {
            "name": "verifyingContract",
            "type": "address"
          }
        ],
        "TransferWithAuthorization": [
          {
            "name": "from",
            "type": "address"
          },
          {
            "name": "to",
            "type": "address"
          },
          {
            "name": "validAfter",
            "type": "uint256"
          },
          {
            "name": "validBefore",
            "type": "uint256"
          },
          {
            "name": "nonce",
            "type": "byte32"
          }
        ]
      },
      "primaryType": "TransferWithAuthorization"
    }
  }
}

2. Customers Sign the Transaction From Their Wallet

You will need to trigger the customer’s wallet using the response from /presign.

For example, if you use the signTypedData function from wagmi, you will need to fill out the domain, types and values fields.

Once the customer signs into the wallet, you will receive a string of raw signatures.

3. Create a Crypto Payment with Customers’ Signature

With a customer’s raw signature, Circle can create a crypto payment with the POST /payment/crypto endpoint.

Curl

curl --location 'https://api-sandbox.circle.com/v1/payments/crypto' \
--header 'X-Requested-Id: ${GUID}' \
--header 'Authorization: Bearer ${YOUR_API_KEY}' \
--header 'Content-Type: application/json' \
--data '{
    "idempotencyKey": "ba943ff1-ca16-49b2-ba55-1057e70ca5c7",
    "paymentIntentId": "4e9fa5b1-3964-4f02-a7ba-811cc5d94be1",
    "protocolMetadata": {
        "type": "TransferWithAuthorization",
        "metaTxNonce": "0xfdb476566b75311fdd14444e6a77630c36e653a3e255adcaa7c34f3babc1de76",
        "signatureValidAfter": "1675104393",
        "signatureValidBefore": "1675107967",
        "rawSignature": "0xcff7ef7a24b88d83fa3d6e81b41c9cef19cc0119c085a6ef98cb1b6bc9436a9f18dcb2d46b9cb4d31a7031466b450bbe1e6c0230c5503c7a68e04055b4be0cbc1b"
    },
    "amount": {
        "amount": "3.14",
        "currency": "USD"
    },
    "source": {
        "address": "0xdB055877e6c13b6A6B25aBcAA29B393777dD0a73",
        "type": "blockchain"
    },
    "destination": {
        "address": "0xda1ab716f7f7b3cb036a7fd74e5ca852126834c1",
        "chain": "ETH"
    },
    "quoteId": "c6ac001e-9812-4bc1-8dc3-1549b5adaa23"
}'

Response

{
  "data": {
    "id":"27827c45-6a3e-4012-8eaa-f6d712f70c2e",
    "type":"payment",
    "status":"pending",
    "amount":{
      "amount":"10.00",
      "currency":"USD"
    }
    "createDate":"2023-02-14T01:21:07.116369Z",
    "updateDate":"2023-02-14T01:21:07.116371Z",
    "merchantId":"a49f9b1d-75e0-44a9-b8d2-4293b3f11ebd",
    "merchantWalletId":"1000563095",
    "paymentIntentId":"dfcf96ab-dd3f-417e-b009-ef899ee4e8da",
    "fromAddresses":{
      "chain":"ETH",
      "addresses":[
        "0xbdE3d06b700A5f622767c85e79e42014C5376B6B"
      ]
    }
    "depositAddress":{
      "chain":"ETH",
      "address":"0x5f1090b5db3e00e13e94b93055b3d1c4254e1720"
    }
  }
}