Marine Credit Union API integration & FDX OpenBanking

OpenData · OpenFinance · FDX · Section 1033 · US credit unions

Connect Marine Credit Union accounts to your stack — under member authorization

Marine Credit Union (com.marinecu.marinecu) is the mobile banking app for Marine CU, a Wisconsin-based not-for-profit cooperative that stewards roughly $1.1 billion in assets and serves more than 76,500 members across four states. We turn what members already see in the app — checking and savings balances, posted and pending transactions, e-statements, scheduled bill payments, debit card controls and Smart ATM locations — into clean, FDX-aligned APIs your platform can consume.

Account login & session APIs — Mirror the Marine Mobile online banking auth handshake, including device binding, MFA challenge and refresh-token rotation. Useful for accounting tools, PFM dashboards and treasury systems that need stable per-member sessions.

Statement & transaction export — Pull posted, pending and scheduled transactions for checking, savings, money market and loan accounts. Paginated by date range, with descriptors normalized for reconciliation against ERP and ledger systems.

Bill pay & recurring transfers — Programmatic access to one-time and recurring payments, scheduled transfers and external account links so AP automation, rent platforms and subscription billers can drive payment events end-to-end.

Branch & Smart ATM locator — Geo-indexed lookup over Marine CU's Smart ATM and branch network for embedded "find a branch" widgets, ITM scheduling and back-office routing.

Data available for integration

The table below maps the data points the Marine Credit Union app surfaces to a typical OpenData / OpenBanking integration target. Field shapes follow the Financial Data Exchange (FDX) v6.x objects so consumers can reuse the same parsers across credit unions.

Data type	Source screen / feature	Granularity	Typical use
Member profile & account list	Login + Accounts overview	Per-member; one record per share, loan, certificate	KYC handoff, onboarding to PFM tools, household roll-ups
Posted transactions	Account detail view	Per transaction, with descriptor, amount, date, running balance	Reconciliation against ERP, double-entry import, tax categorization
Pending & scheduled items	Account detail + Bill Pay	Per item, with effective date and status	Cash-flow forecasting, AP scheduling, fraud monitoring
Balances	Quick-view + dashboard	Real-time available + ledger balance	Underwriting checks, liquidity widgets, low-balance alerts
e-Statements (PDF)	Documents / Statements	Monthly PDFs, 7-year retention typical	Audit trails, mortgage underwriting, accountant handoff
FICO score	Credit dashboard	Numeric + bands, refreshable per member	Lending pre-qualification, credit-builder products
Bill pay payees & events	Bill Pay module	Per payee, per scheduled or sent payment	AP sync, subscription management, recurring-payment dashboards
Card controls	Card management	Per card: lock state, channel toggles, replacement requests	Embedded card lifecycle in third-party admin consoles
Smart ATM & branch network	Locator	Per location: geo, hours, services (deposit-taking, ITM)	Store finders, routing for cash-handling SMBs

Typical integration scenarios

These are real, member-authorized flows we have built or scoped against US credit-union mobile apps. Each maps cleanly onto OpenFinance and Section 1033 patterns.

Accounting and bookkeeping sync. A small business that banks at Marine CU connects its accounting suite to a hosted endpoint that pulls posted transactions every 15 minutes. The integration normalizes Marine descriptors into the FDX Transaction object (postedTimestamp, amount, description, memo, category) so QuickBooks, Xero and NetSuite mappers all consume the same shape. End-to-end, the flow uses OAuth 2.0 with member consent and re-issues tokens on refresh.
Cash-flow underwriting. A community-focused fintech needs 12 months of statements to underwrite a small auto loan. The integration calls /v1/marinecu/statements for a date range, returns FDX-format JSON plus the raw e-Statement PDF, and stores the consent receipt and SHA-256 hash so the audit trail satisfies CFPB-style data-rights logging.
PFM dashboards and budgeting. Personal finance apps poll balances and recent transactions to drive spending insights and round-up savings. The integration honours a 24-hour token TTL, batches refreshes during off-peak hours and falls back to the FICO endpoint for credit-builder modules.
AP automation and recurring rent. A property-management platform schedules monthly rent debits via Bill Pay and listens to webhook events for payment.scheduled, payment.sent and payment.failed. Failed events are routed back to the property manager with a retry hint, and successful events trigger the ledger entry inside the PMS.
Smart ATM and branch locator embed. A travel-money tool embeds Marine CU's deposit-taking Smart ATM network into its in-app map, so members travelling outside La Crosse, Madison, Milwaukee or Fond du Lac can deposit checks without searching the official site.

Technical implementation

1. Member-authorized login (OAuth 2.0 + MFA)

POST /api/v1/marinecu/auth/login
Content-Type: application/json

{
  "username": "<member_login>",
  "password": "<member_password>",
  "device_id": "<trusted_device_uuid>",
  "consent_id": "cns_8e2f...c1"
}

200 OK
{
  "access_token": "<jwt>",
  "refresh_token": "<opaque>",
  "expires_in": 1800,
  "mfa_required": false,
  "fdx_consent": {
    "scope": ["accounts:read", "transactions:read", "statements:read"],
    "expires_at": "2026-08-09T00:00:00Z"
  }
}

2. Statement & transaction export

POST /api/v1/marinecu/statement
Authorization: Bearer <ACCESS_TOKEN>

{
  "account_id": "acc_share_2201",
  "from_date": "2026-04-01",
  "to_date":   "2026-04-30",
  "include":   ["posted", "pending"]
}

200 OK
{
  "account_id": "acc_share_2201",
  "currency": "USD",
  "available_balance": 4218.77,
  "ledger_balance": 4318.77,
  "transactions": [
    {
      "id": "txn_8a91",
      "posted_at": "2026-04-28T15:02:11Z",
      "amount": -42.18,
      "description": "POS DEBIT KWIK TRIP #423 LA CROSSE WI",
      "category": "fuel",
      "running_balance": 4218.77
    }
  ],
  "pagination": {"next_cursor": null}
}

3. Bill Pay webhook (event push)

POST https://your-app.example.com/webhooks/marinecu
X-Signature: t=1715212800,v1=hmac_sha256(payload,secret)

{
  "event": "payment.sent",
  "occurred_at": "2026-05-09T13:45:02Z",
  "payment": {
    "id": "pmt_77b3",
    "payee_id": "pyn_landlord_01",
    "amount": 1450.00,
    "currency": "USD",
    "method": "ACH",
    "memo": "May rent",
    "status": "sent"
  }
}

# Verify HMAC, then upsert payment in your ledger.
# Retry budget: 5 attempts, exponential backoff (2s..256s).

Compliance & privacy

Marine Credit Union is a US-chartered, NCUA-insured credit union, so integrations sit under federal financial-privacy rules. Our deliverables align with the Gramm-Leach-Bliley Act safeguards, the CFPB's Section 1033 personal financial data rights framework, and the Financial Data Exchange standard the CFPB recognized as a standard-setting body in January 2025.

OAuth 2.0 + OIDC for authentication, with refresh-token rotation
FDX 6.4 data shapes for accounts, transactions, statements and consents (Spring 2025 release)
Consent records and access logs retained per GLBA expectations
Scoped tokens, data minimization, and "purpose of use" tagging on every call

Note: in July 2025 the CFPB filed for accelerated rulemaking to revise the Section 1033 rule. We track those updates and adjust consent and pricing flows accordingly.

Typical modules

Auth: login, MFA challenge, token refresh, device binding
Accounts: list, balance, mini-statement, holds
Transactions: paginated history, search, descriptor enrichment
Statements: monthly PDFs + structured JSON
Bill Pay: payees, scheduled and recurring payments, event webhooks
Cards: lock/unlock, channel toggles, replacement requests
Locator: Smart ATMs, branches, deposit-taking ATMs

Data flow / architecture

A typical Marine CU integration runs as a four-stage pipeline. Mobile or server clients drive member-authorized sessions; an ingestion layer normalizes responses into FDX shapes; a storage layer keeps consents, raw payloads and derived rows; an API or analytics layer exposes them to downstream tools.

Marine Mobile / online banking — member grants consent, MFA completes.
Ingestion & protocol layer — our adapter handles auth, paging, retries, and translates raw payloads into FDX Account, Transaction, Statement objects.
Consent + data store — Postgres for structured rows, object storage for PDFs, a consent table keyed by consent_id with TTL and revocation flags.
API gateway / analytics output — REST and webhook endpoints for partner systems; optional warehouse export to BigQuery or Snowflake for reporting.

Market positioning & user profile

Marine Credit Union is a community-focused cooperative based in La Crosse, Wisconsin, with branches across Wisconsin, Minnesota, Iowa and Illinois. The membership skews toward working families, small business owners and first-time borrowers in the Upper Midwest, with a strong emphasis on second-chance lending and financial coaching. The Marine Mobile app supports both Android (com.marinecu.marinecu) and iOS, with Smart ATMs and ITMs providing deposit-taking coverage outside branch hours. Integration buyers are typically PFM startups, small business accounting platforms, regional fintechs and lenders that want a Midwest credit-union footprint alongside Plaid- or MX-aggregated coverage of larger national institutions.

Screenshots

Tap any thumbnail to view a larger version. Imagery is sourced from the official Marine Credit Union Google Play listing and is used here only to illustrate which screens map onto the integration surface.

Similar apps & integration landscape

Marine Credit Union sits inside a broad US credit-union and digital-banking ecosystem. Buyers who integrate Marine CU usually also need parallel coverage for one or more of the apps below. Each entry holds comparable data shapes — accounts, transactions, statements, bill pay — and benefits from the same FDX-aligned API patterns.

UW Credit Union — Madison-based credit union with a feature-rich mobile app (quick balance view, card controls, fast transfers); often paired with Marine CU for Wisconsin coverage.
WESTconsin Credit Union — Mobile deposit and digital wallet support; common in Western Wisconsin reconciliation workloads.
Educators Credit Union — Wisconsin community lender with transfer, bill pay and check-cashing flows similar to Marine Mobile.
Royal Credit Union — Wisconsin and Minnesota footprint, popular for small business members who need balance and transaction sync alongside Marine CU.
Alliant Credit Union — National digital-first credit union; teams integrating Marine CU often also pull Alliant data for members with savings buckets and reward checking.
Bethpage Federal Credit Union — Large East Coast credit union with comparable transaction and statement APIs.
Marine Federal Credit Union — Distinct from Marine CU but frequently confused; integration teams sometimes need both for unified transaction exports.
Alternatives Federal Credit Union — Mission-driven credit union with mobile features that map onto the same FDX object set.
Ally Bank — Digital-only national bank; usually integrated alongside credit-union accounts for households that split deposits.
Chime — Neobank with a SpotMe overdraft cushion; often appears in the same PFM dashboards that consume Marine CU data.

This list is a market overview, not a comparison or ranking. Aggregators such as Plaid, MX and Yodlee already cover most of these institutions; we provide the integration glue when you need deeper, member-authorized coverage of Marine CU itself.

What we deliver

Deliverables checklist

OpenAPI 3.1 specification for every Marine CU endpoint we ship
Protocol and auth flow report (OAuth, MFA, device binding, refresh rotation)
Runnable source for login, statements, balances, bill pay (Python and Node.js)
Webhook receiver template with HMAC verification and retry policy
Automated tests, sandbox fixtures and a Postman collection
Compliance memo: GLBA mapping, FDX 6.4 conformance, Section 1033 consent log layout

Engagement workflow

Scope confirmation: which Marine CU flows and what data fields you actually need.
Protocol analysis and API design (2–5 business days, complexity-dependent).
Build and internal validation against sandbox or member-authorized accounts (3–8 business days).
Documentation, samples and test cases (1–2 business days).
Typical first delivery: 5 to 15 business days; webhook and bill pay extensions may add 3 to 8 days.

About us

OpenFinance Lab is an independent studio focused on mobile-app protocol analysis and OpenData / OpenFinance integrations. Our engineers come from US and EU banks, payment processors, credit-union core providers and cloud-platform teams. We have shipped integrations across consumer banking, lending, brokerage and AP automation, with a strong bias toward FDX-aligned shapes and clean consent records.

Mobile banking, lending, payments and treasury integrations
FDX 6.4 conformance, Section 1033 consent ledger design
Custom Python, Node.js, Go and Kotlin SDKs
Full pipeline: protocol analysis → build → validation → compliance review
Source code delivery from $300 — runnable APIs and full documentation, paid after delivery
Pay-per-call hosted endpoints — no upfront cost, ideal for teams that prefer usage-based pricing

Contact

For quotes, NDAs, or to scope a Marine Credit Union integration, open our contact page:

Contact page

FAQ

What do you need from me to start a Marine Credit Union integration?

The target app name (Marine Credit Union, package com.marinecu.marinecu), the data and flows you actually need (login, statement export, balance sync, bill pay, branch/ATM locator), and any existing online banking credentials or sandbox access you already hold under your own member authorization.

How long does delivery take for a credit union API project?

A first drop with login plus statement export typically lands in 5 to 12 business days. Adding bill pay, recurring transfers, FICO sync and Smart ATM locator usually extends timelines by another 3 to 8 business days depending on multi-factor authentication complexity.

How do you handle compliance with US open banking rules?

We work under member-granted authorization, align data shapes with the FDX (Financial Data Exchange) standard, and respect CFPB Section 1033 personal financial data rights. We document consent records, log access events, and follow GLBA data-minimization guidance. NDAs and security reviews are available on request.

Which delivery model should I choose?

Pick source-code delivery from $300 if you want to host APIs in your own VPC and own the IP. Pick pay-per-call billing if you would rather not run infrastructure and prefer usage-based pricing for low or seasonal volume.

📱 Original app overview (appendix)

Marine Credit Union is a Wisconsin-based, NCUA-insured cooperative headquartered in La Crosse. The credit union stewards roughly $1.1 billion in assets, serves more than 76,500 members across Wisconsin, Minnesota, Iowa and Illinois, and operates 20+ branch and Smart ATM locations. The Marine Mobile app (com.marinecu.marinecu on Android, also available on the App Store) lets members manage their entire financial life from their phone.

According to the official Google Play listing, the app's headline value proposition is: "Marine Mobile puts you in control of your finances. View all your account details in one app, and add your other bank accounts for one complete view of your entire financial life. Set up recurring automatic payments or make one-time payments, pay bills, and add products and services quickly and securely." Members can also "locate Smart ATMs and branch locations from your current location or search by address."

Account aggregation — view Marine balances and add external bank accounts in one place
Bill Pay with one-time and recurring payments, plus scheduled transfers
Mobile check deposit using the phone camera
Free FICO score check inside the app, refreshable without credit-bureau hard pulls
Debit card controls — lock/unlock, channel toggles, replacement requests
Smart ATM and branch locator with geo and address search
Direct deposit switch widget that simplifies routing changes
Eligibility: registered Marine Credit Union online banking user; available on Android and iOS