Working with Routing Number Bank Lookup API

You need to validate a US bank routing number and pull the bank’s legal name, address, phone, ACH capability, and status so you can ship payments or KYC flows without delays. By the end of this guide, you’ll query the Routing Number Bank Lookup API on Zyla API Hub, parse the results, and integrate it into your finance workflows this week.

What this API does and when to use it

The Routing Number Bank Lookup API returns authoritative details for a given US routing number. It can validate whether the routing number is correct and provide the financial institution’s name, branch type (e.g., Main Office), address, phone number, active status, and last update date. Typical use cases include:

Illustration: Working with Routing Number Bank Lookup API

Pre-validating routing numbers on ACH onboarding forms to reduce payment failures.
Enriching bank records in accounting, payout, or treasury systems.
Verifying ACH eligibility before initiating debits or credits.
Building back-office tools for support teams to resolve returned payments quickly.

This API belongs to Finance & Payments on Zyla API Hub, which offers a single account, one API key, and a unified subscription model across more than 10,000 public APIs.

Getting started on Zyla API Hub

To call the endpoints, go to the API listing on Zyla API Hub, click Subscribe or start the trial, and obtain your API key. Authentication is via Authorization: Bearer YOUR_API_KEY in the header.

Billing is subscription + quota (not pay-per-call). The first API offers a 7-day trial or 50 requests. There is no free plan.
For current access options and pricing, check the API page on the marketplace.

Start here: Start 7-day trial on Routing Number Bank Lookup API

Endpoints you’ll use

Below are the available endpoints as listed on the marketplace. Only the explicitly defined parameters are supported—do not add extra keys or request bodies.

1) Get Bank Information

Method: GET

URL: https://zylalabs.com/api/331/routing-number-bank-lookup-api/266/get-bank-information

Description: Get detailed information about a routing number. The endpoint returns the name of the financial institution, the ACH routing number, the branch type, the address, contact information, active status, and the date of the last update.

Required query parameters:

routingnumber (number): e.g., 121000245
paymentType (string): e.g., ach

Copy-paste cURL:

curl -s -X GET "https://zylalabs.com/api/331/routing-number-bank-lookup-api/266/get-bank-information?routingnumber=121000245&paymentType=ach" \
-H "Authorization: Bearer YOUR_API_KEY"

Official example response:

{
"status": "success",
"data": {
"routingNumber": "121000245",
"paymentType": "ach",
"name": "Wells Fargo Bank, Na",
"addressFull": "255 2nd Ave South, Minneapolis, MN 55479",
"street": "255 2nd Ave South",
"city": "Minneapolis",
"state": "MN",
"zip": "55479",
"type": "Main Office",
"phone": "800-245-2426",
"active": true,
"lastUpdated": "2026-07-29"
}
}

Key fields you’ll typically use:

data.routingNumber: The queried routing number, string form.
data.paymentType: For this lookup, “ach” identifies the payment rail context.
data.name, data.addressFull, data.phone: For display, verification, and support workflows.
data.type: Branch type such as “Main Office.”
data.active: Indicates if the routing record is active.
data.lastUpdated: Date string for cache invalidation and auditing.

2) Bank Data

Method: GET

URL: https://zylalabs.com/api/331/routing-number-bank-lookup-api/1353/bank-data

Description: Retrieve detailed information about any bank by looking up its routing number. It also validates whether the provided routing number is correct and returns essential details such as the bank’s name, address, and contact information.

Required query parameters:

number (number): e.g., 304082876

Copy-paste cURL:

Official example response:

Key fields you’ll typically use:

status, success, message: Quick validation and UX messaging.
data.routing_number: The queried number, validated.
data.bank, data.address, data.city, data.state, data.zip, data.phone: Contact and geospatial enrichment.
data.date_of_revision: Useful for reconciliation and audit timelines.

Python example (production-friendly)

The snippet below queries Get Bank Information and safely parses the response. It uses the exact URL and parameters required by the marketplace listing.

import os
import requests
from datetime import datetime

API_KEY = os.getenv("ZYLALABS_API_KEY", "YOUR_API_KEY")
URL = "https://zylalabs.com/api/331/routing-number-bank-lookup-api/266/get-bank-information"
params = {
"routingnumber": "121000245",
"paymentType": "ach"
}
headers = {
"Authorization": f"Bearer {API_KEY}"
}

resp = requests.get(URL, params=params, headers=headers, timeout=15)
resp.raise_for_status()
payload = resp.json()

if payload.get("status") != "success":
raise RuntimeError(f"Lookup failed: {payload}")

bank = payload.get("data", {})
name = bank.get("name")
routing = bank.get("routingNumber")
ach_type = bank.get("paymentType")
active = bank.get("active")
updated = bank.get("lastUpdated") # e.g., "2026-07-29"

# Optional: parse date for cache control or SLA logging
updated_dt = None
if updated:
try:
updated_dt = datetime.strptime(updated, "%Y-%m-%d")
except ValueError:
pass

print({
"routingNumber": routing,
"name": name,
"paymentType": ach_type,
"active": active,
"address": bank.get("addressFull"),
"city": bank.get("city"),
"state": bank.get("state"),
"zip": bank.get("zip"),
"phone": bank.get("phone"),
"type": bank.get("type"),
"lastUpdated": updated
})

Implementation notes that save time

Auth: Always send Authorization: Bearer YOUR_API_KEY.
Transport: Both endpoints are HTTP GET with query parameters; do not include a request body.
Caching: Use data.lastUpdated (Get Bank Information) or data.date_of_revision (Bank Data) to decide when to refresh your cache. Consider a 24–48 hour TTL for stable routing numbers unless your risk posture requires stricter recency.
Validation UX: For Bank Data, surface the message field (e.g., “Routing Bank 304082876 is valid”) inline with your form feedback. Only proceed to payment initiation if success is true.
Normalization: Addresses are returned both as a full string and as components (street, city, state, zip). Prefer the components for consistent formatting in PDFs and emails.
Error handling: Check HTTP status codes and the top-level status/success indicators in the JSON before trusting data fields.
Logging: Record routingNumber/routing_number, name/bank, and lastUpdated/date_of_revision alongside your user/session for audit trails.

End-to-end examples

Use case: ACH onboarding form

On blur of the routing number input, call Bank Data with number set to the 9-digit routing number.
If success is true, display data.bank, city/state, and phone as confirmation for the user.
Optionally, call Get Bank Information with the same routing number and paymentType=ach to confirm active status and branch type before enabling the “Link Account” button.
Cache the results keyed by routing number for the session to avoid repeat lookups.

Use case: Payout rails sanity check

Prior to initiating an ACH credit, call Get Bank Information with paymentType=ach.
Ensure active is true. If false or missing, pause the payout and route the case to support.
Log lastUpdated for compliance and reconciliation reporting.

Use case: Back-office bank enrichment

Batch your routing numbers and iterate calls to Bank Data to enrich bank, address, and phone.
Where available, add Get Bank Information to include branch type and addressFull for agents.
Export normalized fields into your CS tooling so agents can search by city/state during disputes.

Calling from AI agents via MCP

You can drive the same lookups from an AI coding agent or MCP-compatible client using Zyla’s MCP endpoint. Point your MCP client to:

MCP

Set your API key using the apikey query parameter (YOUR_API_KEY). From there, instruct the agent to perform an HTTP GET to the exact Hub URLs shown above, including required query parameters and the Authorization header. The agent will receive the same JSON structures, so you can chain tool calls (e.g., validate a routing number, then render a formatted confirmation) inside your agent workflows.

Endpoint recap and field mapping

Get Bank Information (GET)
- URL: https://zylalabs.com/api/331/routing-number-bank-lookup-api/266/get-bank-information
- Params: routingnumber (number), paymentType (string)
- Returns: routingNumber, paymentType, name, addressFull, street, city, state, zip, type, phone, active, lastUpdated
Bank Data (GET)
- URL: https://zylalabs.com/api/331/routing-number-bank-lookup-api/1353/bank-data
- Params: number (number)
- Returns: status, success, message, data.routing_number, data.date_of_revision, data.new_routing_number, data.bank, data.address, data.city, data.state, data.zip, data.phone

Operational guidance

Security: Store YOUR_API_KEY in your server-side environment, not in client-side code.
Retries: For transient 5xx responses, apply exponential backoff. Do not retry validation failures (where success is false or status indicates an invalid number); fix inputs instead.
Observability: Log both the request parameters and the returned status/success to troubleshoot user-entered routing numbers.
Internationalization: These endpoints are designed for US routing numbers. Avoid applying them to non-US account identifiers.
Change management: Use lastUpdated and date_of_revision signals to alert your team or to trigger re-validation flows if data has meaningfully changed.

Quick reference cURLs

Get Bank Information (ACH):

Bank Data (validate routing):

Where to go next

Explore this and other Finance & Payments APIs on Zyla API Hub. Create your account, subscribe, and use a single API key across multiple services to accelerate your integration. When you’re ready to test live, start here: Start 7-day trial on Routing Number Bank Lookup API. You can also browse more APIs anytime from the Zyla API Hub catalog.

FAQ

Is there a request body for these endpoints?
No. Both endpoints are GET with query parameters only. Do not send a JSON body.

How do I authenticate?
Add Authorization: Bearer YOUR_API_KEY to the request headers.

Can I use these endpoints to check non-ACH rails?
Get Bank Information requires paymentType=ach when calling the sample path provided. If you need other rails, check the API page for available options.

What should I cache?
Cache the response per routing number. Use lastUpdated (Get Bank Information) or date_of_revision (Bank Data) to decide when to refresh.

Is there a free plan?
There is no free plan. The first API offers a 7-day trial or 50 requests. See the API listing for current access options.