Split Bills - Group Expenses API integration & OpenData services

1. Account & consent layer

Mirror of the app's account binding flow. Issues a per-user access token (OAuth-style), supports refresh, and exposes a consent record (which group, which scopes, expiry). Use it for: linking a Split Bills - Group Expenses user to a budgeting platform with a one-click bind.

2. Group ledger API

List groups (trip, flatshare, event, custom), retrieve member rosters with display names, and walk a group's expense history. Supports cursor, from_date, to_date, and currency filters. Use it for: monthly trip recap reports and shared-living dashboards.

3. Multi-currency expense export

Each expense returns original currency, original amount, FX rate snapshot, and home-currency equivalent. Mirrors how Splid (150+ currencies, added in 2024) and Splitwise (Open Exchange Rates) handle international trips. Use it for: travel ERP imports and per-trip cost analysis.

4. Debt graph & settlement API

Returns the net position per member and the simplified pairwise debt graph (the same problem Tricount and Splitwise solve with integer-programming-style reduction). Use it for: settle-up suggestions, debt collection reminders, and CFO-style end-of-month group close-outs.

5. Webhook & event stream

Subscribe to expense.created, expense.updated, settlement.recorded, and group.member.added. Use it for: real-time push of new shared expenses into a household budget app or a corporate travel reimbursement workflow.

6. Bulk export & reporting

One-shot endpoint that bundles a group (or all groups for a user) into JSON, CSV, PDF, or Excel — comparable to the paid export features in Splitwise Plus, Settle Up, and Splid. Use it for: tax season prep, expense audits, and sharing settled trips with non-app participants.

Scenario A — Travel ERP & reimbursement sync

Context: A small travel agency wants every shared trip cost from Split Bills - Group Expenses to flow into its expense-reimbursement system, in the corporate base currency, with the correct payer.

Data / API: GET /v1/groups, GET /v1/groups/{id}/expenses?currency=base&from_date=..., plus the FX snapshot field.

OpenFinance mapping: Each expense becomes a normalised "transaction" event with payer-as-account-holder, mirroring how OpenBanking transaction feeds are consumed by reimbursement platforms.

Scenario B — Flatshare household budget dashboard

Context: A property-management SaaS wants tenants to share the running utility / groceries ledger into a household dashboard, with month-end totals per tenant.

Data / API: GET /v1/groups/{id}/balances, plus webhook on expense.created.

OpenFinance mapping: Net balances become "obligations" surfaced alongside rent and bills, similar to how open banking feeds surface bill-pay categories.

Scenario C — Multi-currency trip recap for a travel app

Context: A travel-planner app (in the same space as MemoGo) wants an end-of-trip cost recap, in each member's home currency, with charts.

Data / API: GET /v1/groups/{id}/export?format=json, GET /v1/groups/{id}/debts/simplified.

OpenData mapping: The trip ledger is published as a portable JSON document — the user owns the export and can hand it to any downstream tool, in line with GDPR Article 20 data portability.

Scenario D — Settle-up handoff to an open-banking payment rail

Context: A European fintech wants Split Bills - Group Expenses settlements to trigger an actual bank transfer through a PSD2 payment-initiation provider, similar to the Tricount × Mastercard × Aion Bank flow announced for Belgian users.

Data / API: Webhook on settlement.recorded → handoff to a PSD2 PIS provider with payer/payee/amount/currency.

OpenBanking mapping: The integration acts as the "trigger" half of a PSD2 payment-initiation flow; the licensed payment provider handles the regulated leg.

Scenario E — Personal-finance aggregator import

Context: A budget-tracking app wants to pull group expenses into a user's personal feed so out-of-pocket trip costs are no longer invisible to their monthly budget.

Data / API: GET /v1/me/expenses?role=payer with a long-tail history endpoint.

OpenData mapping: Out-of-pocket expenses become part of the user's complete financial picture, alongside their bank-feed transactions.

What you receive

• OpenAPI / Swagger specification for every endpoint we expose
• Protocol analysis report covering login, session, and ledger calls
• Runnable source code in Python (FastAPI) and Node.js (Express)
• Webhook reference implementation with retry & signing
• Postman collection plus end-to-end test cases
• Compliance notes (consent record format, data-retention guidance)

Login & consent (pseudocode)

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

{
  "user_handle": "alice@example.com",
  "device_id":   "ios-7b3c...",
  "scopes":      ["groups.read","expenses.read","balances.read"]
}

200 OK
{
  "access_token":  "eyJhbGciOi...",
  "refresh_token": "rt_3f9c2c...",
  "expires_in":    3600,
  "consent_id":    "cns_2026_04_29_a1b2"
}

Group ledger query (pseudocode)

GET /api/v1/splitbills/groups/grp_lisbon_2026/expenses
  ?from_date=2026-04-01
  &to_date=2026-04-30
  &currency=EUR
  &cursor=eyJwYWdlIjoxfQ
Authorization: Bearer <ACCESS_TOKEN>

200 OK
{
  "group_id": "grp_lisbon_2026",
  "base_currency": "EUR",
  "expenses": [
    {
      "id": "exp_001",
      "date": "2026-04-12",
      "payer_id": "usr_alice",
      "original": { "amount": 84.50, "currency": "USD" },
      "converted": { "amount": 78.10, "currency": "EUR", "fx_rate": 0.9243 },
      "category": "food",
      "note": "Tasca dinner",
      "splits": [
        { "member_id": "usr_alice", "share": 26.04 },
        { "member_id": "usr_ben",   "share": 26.03 },
        { "member_id": "usr_chloe", "share": 26.03 }
      ]
    }
  ],
  "next_cursor": "eyJwYWdlIjoyfQ"
}

Settlement webhook (pseudocode)

POST https://your-app.example.com/webhooks/splitbills
X-SplitBills-Signature: t=1714400000,v1=ab12cd...
Content-Type: application/json

{
  "event":   "settlement.recorded",
  "consent_id": "cns_2026_04_29_a1b2",
  "data": {
    "group_id":  "grp_lisbon_2026",
    "from":      "usr_ben",
    "to":        "usr_alice",
    "amount":    52.07,
    "currency":  "EUR",
    "occurred_at": "2026-04-29T14:21:00Z"
  }
}

// Error response shape (4xx / 5xx)
{ "error": { "code": "consent_revoked",
             "message": "User has revoked groups.read scope.",
             "retryable": false } }

Who we are

We are an independent technical studio specialised in App interface integration and authorized API integration. Our core team has spent years building inside mobile apps, payment gateways, and OpenBanking pipelines — so we understand both the inside of an app like Split Bills - Group Expenses and the outside of the systems that need to consume its data.

• Protocol analysis & interface refactoring across Android and iOS
• OpenData / OpenFinance / OpenBanking integration design
• Custom Python, Node.js, and Go SDKs with full test harnesses
• Compliance-aware deliveries (GDPR, PSD2, CCPA, regional rules)
• End-to-end pipeline: protocol analysis → build → validation → handover

Contact & engagement models

Two ways to engage:

• Source code delivery from $300 — runnable API source code plus full documentation; you pay after delivery, on satisfaction.
• Pay-per-call API billing — call our hosted endpoints and pay only for what you use; no upfront cost.

Open contact page

Engagement workflow

1. Scope confirmation — which surfaces of Split Bills - Group Expenses you need (ledger only, ledger + settlement, ledger + webhook).
2. Protocol analysis & API design (2–5 business days, complexity-dependent).
3. Build & internal validation against a synthetic dataset (3–8 business days).
4. Documentation, sample clients, Postman collection, test cases (1–2 business days).
5. Typical first delivery: 5–15 business days. Pay-per-call clients can usually start within 48 hours.

FAQ

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