You can obtain the funding source URL which identifies the account by calling the API to list your Customer's funding sources. 

If your application didn't store the FundingSourceId after it was initially created, you can retrieve your and search your customers funding sources via the API.

Sandbox - GET https://api.dwolla.com/customers/{id}/funding-sources
Production - GET https://api.dwolla.com/customers/{id}/funding-sources 

Example Request and Response - 

GET https://api-sandbox.dwolla.com/customers/5b29279d-6359-4c87-a318-e09095532733/funding-sources
Accept: application/vnd.dwolla.v1.hal+json
Authorization: Bearer pBA9fVDBEyYZCEsLf/wKehyh1RTpzjUj5KzIRfDi0wKTii7DqY 
{"_links": {
    "self": {
      "href": "https://api-sandbox.dwolla.com/customers/5b29279d-6359-4c87-a318-e09095532733/funding-sources"
    },
    "customer": {
      "href": "https://api-sandbox.dwolla.com/customers/5b29279d-6359-4c87-a318-e09095532733"
    }
  },
  "_embedded": {
    "funding-sources": [
      {
        "_links": {
          "self": {
            "href": "https://api-sandbox.dwolla.com/funding-sources/ab9cd5de-9435-47af-96fb-8d2fa5db51e8"
          },
          "customer": {
            "href": "https://api-sandbox.dwolla.com/customers/5b29279d-6359-4c87-a318-e09095532733"
          },
          "with-available-balance": {
            "href": "https://api-sandbox.dwolla.com/funding-sources/ab9cd5de-9435-47af-96fb-8d2fa5db51e8"
          }
        },
        "id": "ab9cd5de-9435-47af-96fb-8d2fa5db51e8",
        "status": "verified",
        "type": "balance",
        "name": "Balance",
        "created": "2015-10-02T21:00:28.153Z",
        "removed": false,
        "channels": []
      },
      {
        "_links": {
          "self": {
            "href": "https://api-sandbox.dwolla.com/funding-sources/98c209d3-02d6-4bee-bc0f-61e18acf0e33"
          },
          "customer": {
            "href": "https://api-sandbox.dwolla.com/customers/5b29279d-6359-4c87-a318-e09095532733"
          }
        },
        "id": "98c209d3-02d6-4bee-bc0f-61e18acf0e33",
        "status": "verified",
        "type": "bank",
        "bankAccountType": "checking",
        "name": "Jane Doe’s Checking",
        "created": "2015-10-02T22:03:45.537Z",
        "removed": false,
        "channels": [
            "ach"
        ],
        "fingerprint": "4cf31392f678cb26c62b75096e1a09d4465a801798b3d5c3729de44a4f54c794"
      }
    ]
  }
}

For more information, refer to our developer documentation. 

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