Reaching the loan ledger and repayment schedule inside VayDễ

A VayDễ loan does not sit still. Interest accrues every day — about 0.05% of the outstanding principal, capped at 18% a year as the app describes its own terms — so the figure worth integrating is a moving repayment schedule, not a one-off balance. The product issues short-term consumer loans in Vietnam, roughly 900,000 to 40,000,000 VND over 91 to 360 days per its Play Store listing, and every borrower's record — application, decision, disbursement, installments — lives on the lender's backend behind a phone-number login. That backend is the target here.

What sits behind a VayDễ login

The app's own screens map cleanly onto the records its server keeps. Here is what an integrator would actually work with, named the way VayDễ presents it.

Authorized routes to the repayment data

Four routes genuinely apply to an app shaped like this. They differ in reach, effort and how long they keep working.

Authorized interface integration

We observe the mobile client's own traffic — the login and token exchange, the active-loan call, the schedule call — under a borrower who has authorized the work, then implement a clean client against those same surfaces. This reaches the full ledger the moment the app does, and it is the route that pays off fastest for VayDễ. Access to a consenting account is arranged with you during onboarding.

Regulated Open API under SBV Circular 64

Circular 64/2024/TT-NHNN brought bank Open APIs into a defined regime on 1 March 2025, with OAuth 2.0, TLS 1.2+, and revocable time-bound consent. Where VayDễ's disbursing bank partner exposes account data through that catalog, the borrower's bank-side records become reachable by consent. This is the most durable route as the regime matures toward its 1 March 2027 compliance date.

User-consented credential session

The borrower authenticates in a controlled session and we pull only their own records. It fits one-off migrations and audits where standing automation is not needed.

Native artifact parsing

The app produces an electronically signed loan agreement and contract figures; where a borrower can export that document, we parse it as a backstop for the contract terms and schedule.

For a project that needs the data this quarter, we'd build against the consented-session interface route — it reaches the whole loan ledger today and does not wait on the lender joining an Open API catalog. Where VayDễ or its disbursing bank is already inside the SBV sandbox, we fold the Circular 64 consent flow in as the longer-lived path and keep the interface client as the working implementation underneath.

A repayment-schedule pull, sketched

Illustrative shapes, not copied from the wire. Exact paths and field names are confirmed during the build, and every call runs under the consenting borrower's session with token refresh on expiry.

# auth → active loan → schedule  (illustrative)

POST /api/v1/auth/login
  { "phone": "+84xxxxxxxxx", "device_id": "…", "otp": "xxxxxx" }
  → 200 { "access_token": "…", "refresh_token": "…", "expires_in": 3600 }

GET /api/v1/loans/active
  Authorization: Bearer <access_token>
  → 200 {
      "loan_id": "ln_…",
      "principal_vnd": 5000000,
      "term_days": 120,
      "annual_rate": 0.18,
      "disbursed_at": "2026-03-01",
      "outstanding_vnd": 4150000      # re-derived per read, not cached
    }

GET /api/v1/loans/{loan_id}/schedule
  → 200 { "installments": [
      { "due_date": "2026-04-01", "principal_vnd": 1250000,
        "interest_vnd": 75000, "status": "paid" },
      { "due_date": "2026-05-01", "principal_vnd": 1250000,
        "interest_vnd": 75000, "status": "due" }
      // …
    ] }

# on 401 → refresh token, retry once; reads are idempotent.
# daily interest ≈ principal × 0.05% (75,000 VND/mo on a 5,000,000 loan
#   per the listing's worked example).

What lands in your repository

Every deliverable is anchored to the surfaces above, not a generic kit.

• An OpenAPI 3 spec covering the auth exchange, active-loan and schedule endpoints, with the response fields VayDễ actually returns.
• A protocol and auth-flow report: the token and refresh chain as observed, headers and device-binding behavior, error and retry semantics.
• Runnable source in Python and Node.js for login, loan-status, schedule retrieval and disbursement-reference reconciliation.
• Automated tests with recorded fixtures so the client can be verified without a live borrower session on every run.
• Interface documentation a developer can hand to the next engineer, plus data-retention guidance aligned to Vietnam's PDPL.

Consent and Vietnam's data rulebook

Three instruments shape this work, and all three are in force as of mid-2026. The State Bank of Vietnam's Circular 64/2024/TT-NHNN governs bank Open APIs from 1 March 2025 — OAuth 2.0, transport encryption, and consent that the user can revoke and that expires. Decree 94/2025/ND-CP opened a regulatory sandbox from 1 July 2025 covering P2P lending, Open API and credit scoring, with consent-based data sharing and use of National Credit Information Centre (CIC) data among its named pillars. And the Personal Data Protection Law (Law 91/2025/QH15), in effect since 1 January 2026 with Decree 356/2025 alongside it, treats financial account details as sensitive personal data — consent must be given per purpose, and breaches touching financial or biometric data carry a 72-hour notification duty.

The dependable basis we build on is the borrower's own authorization. We record consent scope, honor revocation, pull only the fields a use case needs, and keep an access log. Where a project needs it, the work runs under an NDA. The Open API regime is described here as where a durable route is heading, not as a switch already flipped for this particular lender.

What we plan around on a lender build

A consumer-loan app carries a few specifics that decide whether an integration stays correct. These are things we account for, handled with you as part of the engagement.

• We model the daily interest accrual rather than caching a balance. At roughly 0.05% a day, a snapshot stored overnight already disagrees with the lender's figure, so a pulled outstanding amount is re-derived from the disbursement date and rate on each read.
• We design the sync around the consent and token-refresh window. Loans run 91 to 360 days, so an integration has to survive token rotation across months without the authorized session silently lapsing in the middle of a collection cycle.
• We keep KYC field handling minimal. CMND/CCCD numbers are sensitive data under the PDPL, so the client requests only what the use case justifies and logs each access rather than vacuuming the whole profile.
• We add a re-validation pass for app updates. When the mobile front end or an endpoint shape changes between versions, a small fixture-checked suite flags the drift before it reaches production.

Pricing and handover

The loan-status and repayment-schedule client is the core of what ships. Source-code delivery starts at $300: you get the runnable client, the spec, tests and docs in your own repository, and you pay after delivery once it works against a consenting account to your satisfaction. Prefer not to host it yourself? Take the pay-per-call hosted API instead, where we run the endpoints and you pay only for the calls you make, with no upfront fee. Either path runs on a one-to-two-week cycle. Tell us the app and what you need from its data, and we handle the access, the protocol work and the compliance posture — start the conversation here.

Screens we mapped

The store screenshots we worked from, showing the application, approval and repayment surfaces. Select one to enlarge.

Keeping a pulled balance honest

Freshness is the part most teams underestimate with a lending app. Because accrual is daily and statuses flip from due to overdue on a calendar boundary, a sync that runs once and forgets goes wrong quietly. We set the read cadence to the loan's billing rhythm, re-derive interest at read time, and treat the front-end version string as a trip-wire: if the client changes, the fixture suite fails first and we patch before any bad data lands. A short maintenance window each release keeps the client tracking the app rather than chasing it after the fact.

Similar apps in the same integration set

A unified view of Vietnamese consumer lending usually means several of these alongside VayDễ. Each holds comparable per-borrower data behind its own login.

• Doctor Dong — short-term online cash loans; per-borrower application and repayment records behind an account.
• Tima — a P2P lending marketplace matching borrowers and lenders; application, matching and repayment data.
• FE Credit — consumer finance lender; installment loan accounts and statements behind a login.
• Home Credit Vietnam — point-of-sale and cash installment loans; per-customer contract and schedule data.
• Vietdong (Vay nhanh online) — online cash loans of 1–50M VND over 91–365 days; a loan ledger inside the app.
• EasyCash (vay tiền online) — online lending with application and repayment tracking per user.
• LoanHub Vietnam — a loan aggregation app surfacing multiple lenders; application and offer data.
• VayDễDàng — fast online loan app with similar application and repayment surfaces.
• Timo (BVBank) — installment loans inside a digital bank; account and repayment records.
• Easy Credit (Tài chính số) — digital consumer finance; loan account and statement data.

What we checked

This mapping rests on the app's own Play Store listing for its terms, amounts and flow, and on primary legal and regulatory write-ups of Vietnam's Open API, sandbox and data-protection rules, read in June 2026. Specific sources: the VayDễ Play Store listing; an industry analysis of Circular 64/2024/TT-NHNN on Open APIs; DFDL on the Decree 94/2025 fintech sandbox; and Hogan Lovells on the Personal Data Protection Law (Law 91/2025).

Mapped by the OpenBanking Studio integration desk · 2026-06-24.

Questions integrators ask about VayDễ

Which VayDễ surfaces actually carry the structured data?

The loan dashboard holds the outstanding principal and accrued interest; the repayment screen holds the installment list with per-installment due date, principal portion, interest portion and status; the application flow holds the requested amount, term and approval decision; and the disbursement step exposes the linked bank or e-wallet reference. Those four are where an integrator gets real records, not marketing copy.

Does Vietnam's Open API rule change how we reach VayDễ data?

Circular 64/2024/TT-NHNN took effect on 1 March 2025 and sets OAuth 2.0, TLS and consent-management standards for bank Open APIs, with full compliance due by 1 March 2027. Where VayDễ or its disbursing bank sits inside that catalog or the Decree 94/2025 sandbox, consent-based Open API access becomes a durable route. Until that applies to this lender, we work through authorized interface integration under the borrower's own consent.

How do you keep a pulled balance matching VayDễ's own figure?

Interest accrues daily — about 0.05% of the outstanding principal, capped at 18% a year as the app states its terms — so a cached balance drifts within hours. We timestamp every read and re-derive accrual from the disbursement date and rate rather than storing a number that goes stale, so a pulled figure reconciles to the lender's on any given day.

Can you reconcile disbursements against the borrower's bank account?

Yes. The payout reference appears at the disbursement step, when funds are sent to the borrower's payment account, so we match that reference against the rail and the schedule's first due date. That ties a VayDễ loan record to the money movement behind it for collections and reconciliation.