K Bank (케이뱅크) API integration & OpenBanking services

1. Accounting & ERP sync for SMEs

Korean small businesses opening accounts through K Bank's CEO Home need their daily inflows and outflows pushed into accounting software (e.g. Douzone, SAP, NetSuite). We map K Bank statement records to GL line items, tag counterparties, and post nightly via webhook. Fields involved: account_no, tran_date, tran_amt, balance_after, counter_party_name. This sits naturally on top of the KFTC OpenBanking /v2.0/account/transaction_list/fin_num family, with our adapter handling pagination, retries and timezone normalisation.

2. Crypto exchange reconciliation (Upbit on/off-ramp)

Because K Bank is the named KRW deposit partner for Upbit, exchanges, market-makers and tax tools all need to reconcile K Bank deposit/withdrawal events against on-chain or order-book activity. Our integration emits an UpbitLinkedTxn event with tx_id, direction, krw_amount, exchange_ref, status, ready to join with Upbit's REST records — important for both accounting and Korea's virtual-asset reporting obligations.

3. Wealth aggregation across Korean digital banks

End users typically hold balances at K Bank, Kakao Bank and Toss Bank simultaneously. A wealth or PFM app can register K Bank under user consent, then unify balance, deposit-product and savings-goal data into a single timeline. This scenario maps each K Bank "Discover for Me" subscription record to a normalised Holding object, then merges it with parallel exports from competing apps.

4. Compliance & AML monitoring

Compliance teams ingest the K Bank statement firehose into transaction-monitoring engines (SAS, Actimize, in-house Spark jobs) to flag unusual patterns. We hand over normalised JSON with stable field names plus a hashed customer ID, so analysts can run rules without exposing full PII. Auth events from joint-certificate refresh and mobile-OTP usage are emitted on a separate stream for behavioural risk scoring.

5. Project Pax-style cross-border stablecoin pilots

K Bank announced Project Pax in 2024, a KR↔JP remittance proof-of-concept using stablecoins. For partners exploring similar pilots we build a sandboxed adapter: K Bank KRW debit → stablecoin minting service → counterpart bank in JP/SG. Even when pilot APIs are not public, the page-1 integration target is still a clean K Bank statement and balance feed against which to settle.

Auth: token exchange aligned to KFTC OAuth 2.0

POST /oauth/2.0/token HTTP/1.1
Host: openapi.kbank-adapter.local
Content-Type: application/x-www-form-urlencoded

code=AUTH_CODE_FROM_USER_CONSENT
&client_id=YOUR_CLIENT_ID
&client_secret=YOUR_CLIENT_SECRET
&redirect_uri=https://your.app/callback
&grant_type=authorization_code

200 OK
{
  "access_token": "eyJhbGciOi...",
  "token_type": "Bearer",
  "expires_in": 7776000,
  "refresh_token": "rt_...",
  "scope": "login inquiry transfer",
  "user_seq_no": "1101234567"
}

Statement query (transaction list by fin_num)

GET /v2.0/account/transaction_list/fin_num
  ?bank_tran_id=M202504030U000123456
  &fintech_use_num=199167111111111111111111
  &inquiry_type=A
  &inquiry_base=D
  &from_date=20260401&to_date=20260430
  &sort_order=D
  &tran_dtime=20260504130000
Authorization: Bearer eyJhbGciOi...

200 OK
{
  "api_tran_id": "...",
  "rsp_code": "A0000",
  "balance_amt": "5180230",
  "res_list": [
    {"tran_date":"20260428","tran_time":"103021",
     "inout_type":"입금","tran_amt":"120000",
     "after_balance_amt":"5180230",
     "branch_name":"케이뱅크","print_content":"UPBIT 출금"}
  ]
}

Webhook: real-time transaction push

POST /webhooks/kbank/txn HTTP/1.1
Host: client.example.com
X-OFL-Signature: t=1746360000,v1=hex_hmac_sha256

{
  "event": "txn.posted",
  "occurred_at": "2026-05-04T05:00:00Z",
  "account_no_masked": "100-2****-1234",
  "fintech_use_num": "199167...",
  "amount_krw": -35000,
  "channel": "MOBILE_TRANSFER",
  "counterparty": "쿠팡(주)",
  "balance_after": 5145230,
  "auth_method": "MOBILE_OTP"
}

Error handling & idempotency

Every K Bank request carries a client-side bank_tran_id (M + sequence + date) and an Idempotency-Key header on our side, so a network retry never double-posts a transfer or double-bills a pay-per-call statement query. Common KFTC error codes (A0001 invalid token, A0006 rate limit, O0001 downstream bank busy) are mapped to typed exceptions in the SDK and exposed as RFC 7807 problem JSON to API consumers, with retry hints attached.

Korean regulatory alignment

Korea's open banking is centrally operated by the Korea Financial Telecommunications & Clearings Institute (KFTC) and supervised by the Financial Services Commission (FSC) and Financial Supervisory Service (FSS). Our integrations follow the KFTC REST OpenBanking specification (account inquiry, transaction inquiry, transfer, holder verification) and respect Korea's Personal Information Protection Act (PIPA) for consent capture, retention and cross-border transfer.

Authorization-only data access

We never bypass K Bank's joint-certificate, mobile-OTP, or one-device registration controls. Per the K Bank security policy, the service runs only on a single registered device, and rooted handsets are rejected — our adapter respects those rules and surfaces them as explicit error codes rather than hiding them. Where a client needs deeper access (CEO Home admin, internal dashboards), we require a written authorization scope and an NDA.

Permissions mirroring

The K Bank Android manifest distinguishes required permissions (Phone, App Usage Information) from optional ones (Contacts, Camera, Storage). Our integration requests only the equivalent server-side data needed for each API call, with field-level minimisation: e.g. statement APIs strip counterparty memos when the consent scope does not include them.

Deliverables checklist

• OpenAPI 3.1 specification covering login, balance, statement, transfer, webhook
• Protocol & auth flow report (OAuth 2.0 token chain, joint-certificate refresh, OTP flow)
• Runnable source for Python (FastAPI) and Node.js (Express) adapters
• Postman collection + automated pytest / vitest test harness
• Deployment guide for Docker / Kubernetes (Korea region preferred)
• Compliance briefing: PIPA, KFTC, FSC, FSS, virtual-asset reporting

Engagement workflow

1. Scope confirmation: which data sets, regions, volumes (1–2 days)
2. Protocol analysis & KFTC sandbox setup (3–6 business days)
3. Adapter build & internal validation (5–10 business days)
4. Docs, samples, test fixtures, deployment handover (2 business days)
5. Go-live with monitoring & on-call SLA

Kakao Bank (카카오뱅크)

The largest Korean internet-only bank, with messenger-driven UX and very deep retail penetration. Teams that already integrate K Bank often need a parallel Kakao Bank statement export so a single PFM dashboard can show all balances together.

Toss Bank (토스뱅크)

The third internet-only bank, run by Viva Republica (Toss). Its appeal is super-app integration with payments, brokerage and credit scoring, so unified API access alongside K Bank is common for fintech analytics and credit risk products.

Shinhan Sol (신한 쏠)

Shinhan Bank's all-in-one app, a major commercial-bank competitor. For corporate clients moving payroll between Shinhan and K Bank, harmonised statement APIs make month-end reconciliation far cheaper than scraping each app separately.

KB Star Banking

KB Kookmin's flagship banking app and one of Korea's most-used finance apps. Often surfaces in the same wealth-aggregation projects as K Bank because households split deposits between traditional and digital banks.

Woori One Touch

Woori Bank's primary mobile banking app, important for FX-heavy SMEs. Pairs naturally with K Bank for businesses that hold KRW operating balances at K Bank but use Woori for cross-border wires.

Hana 1Q Bank (하나원큐)

Hana Bank's mobile banking app, with strong overseas remittance and FX features. Useful in cross-border data integrations alongside K Bank's Project Pax-style stablecoin remittance pilots.

NH Smart Banking (NH 스마트뱅킹)

NongHyup Bank's app, dominant in agricultural and rural segments. SMEs with rural and urban operations often hold both NH and K Bank accounts, making joint statement export a frequent ask.

Toss (토스 super-app)

The Toss super-app (separate from Toss Bank) covers payments, MyData aggregation and investments. Integrators often pull MyData-style aggregation from Toss and detailed bankbook data from K Bank in the same pipeline.

KakaoPay (카카오페이)

Korea's leading digital wallet and payments app. Not a bank, but its transaction stream often needs reconciling against the K Bank account that funds it, especially for merchants and gig workers.

Naver Pay (네이버페이)

The Naver-led payments and rewards platform, embedded in Korea's largest e-commerce surfaces. Sellers need their Naver Pay settlements joined to K Bank deposit records for accurate revenue accounting.

Who we are

OpenFinance Lab is an independent technical studio focused on App interface integration and authorized API integration. Our engineers come from Korean and international banks, payment gateways, mobile-protocol research and cloud platform teams. We have shipped end-to-end integrations against KFTC OpenBanking, Japanese zengin clearing, India's UPI rails and SWIFT messaging — under privacy and compliance constraints in each region.

• Mobile app protocol analysis (Android & iOS), authorized API integration, OpenData / OpenFinance pipelines
• Two engagement models: source-code delivery from $300 (pay after delivery upon satisfaction) and pay-per-call hosted API access (no upfront cost)
• Custom Python, Node.js, Go and Kotlin SDKs with OpenAPI documentation and CI test harnesses
• Marketed to overseas clients, familiar with mainstream Apps' interface standards across Korea, Japan, India, EU and the US

Contact

To request a quote for K Bank (케이뱅크) integration or any other app, send your target app name and concrete data requirements via our contact page.

Contact page

Typical first response within one business day. NDA available before disclosing app credentials.

Which K Bank data can you actually expose through an API?

Account login state, balance per bankbook, deposit and savings products, transaction history with paging and date filters, joint-certificate and OTP authentication events, Upbit-linked deposit and withdrawal records, and benefit/event redemption status. Outputs can be JSON, Excel, or PDF statements aligned with KFTC OpenBanking record formats.

Is this aligned with Korea's OpenBanking and KFTC rules?

Yes. Korea's open banking is centrally operated by KFTC and offered as REST web services. Where official KFTC endpoints exist (account inquiry, transaction inquiry, transfer, holder verification), we use them. For app-only data (events, benefits, CEO Home), we work under explicit user consent and authorized protocol analysis only.

How long does a first delivery take?

Login and statement APIs typically ship in 5–12 business days. Deeper flows like Upbit-linked reconciliation, joint-certificate refresh, or multi-account CEO Home aggregation can extend to 3–4 weeks depending on KFTC sandbox approval timing.

What do you need from the client to start?

Target app name (already provided: 케이뱅크), the concrete data you want to consume (e.g. transaction history, balance, statements, Upbit deposits), any KFTC OpenBanking sandbox or production credentials, and a written authorization scope so we can satisfy Korean privacy and financial regulations.