Routing Number API in Python: 021000021 as JSON

A routing number API in Python posts a 9-digit ABA number and reads the bank. On BankDataStack that is POST /api/v1/routing/validate with X-API-Key. Official example: 021000021.

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Request: official 021000021

curl -X POST https://www.bankdatastack.com/api/v1/routing/validate \
-H "X-API-Key: YOUR_API_KEY" \
-H "Content-Type: application/json" \
-d '{"routing_number": "021000021"}'

Python: same contract

import json, os, urllib.request
req = urllib.request.Request(
"https://www.bankdatastack.com/api/v1/routing/validate",
data=json.dumps({"routing_number": "021000021"}).encode(),
headers={"X-API-Key": os.environ["BANKDATA_KEY"], "Content-Type": "application/json"},
)
print(urllib.request.urlopen(req).read().decode())

Response: official ACH sample (lastUpdated 2025-11-12)

{
"status": "success",
"data": {
"routingNumber": "021000021",
"paymentType": "ach",
"name": "Jpmorgan Chase Bank, Na",
"city": "Tampa",
"state": "FL"
}
}

Wire on the same RTN resolves New York. Do not invent a Korean IBAN.

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Validate a routing number in Python →