Settle Up – Group Expenses API integration (OpenData / OpenFinance)

Transaction history API

Pull expenses and incomes for a group: amount, currency, payer(s), participant list, split weights, category, note, created/updated timestamps, and a receipt-photo reference. Use it for monthly reconciliation, trip cost reports, or feeding a bookkeeping ledger so itemised bar tabs and grocery runs land in the right account.

Balance & net-position sync

Read each member's running balance and the group's aggregate position. This drives "settle up" reminders, roommate dashboards, or a treasurer view that flags when one person has fronted too much before a trip ends.

Settlement / transfer plan endpoint

Return the minimised set of transfers that clears the group (Settle Up's core "minimise the number of transfers" logic). Hand those instructions to a payment screen or export them as a payout list for a finance team.

Multi-currency & FX module

Normalise mixed-currency groups into one reporting currency using real-time exchange rates, keeping both the original and converted amounts. Useful for cross-border travel groups and for audit trails that must show the rate applied on the expense date.

Member statistics & category analytics

Aggregate spend by member, by category (including the AI-assisted categories Settle Up began auto-filling in 2024) and by period. Plug it into a budgeting dashboard or a "where did the holiday money go" summary email.

Export & webhook automation

Wrap the existing CSV / Excel exports into a scheduled job that drops files to S3, Google Drive or an SFTP target, and emit a webhook when a group changes so downstream systems refresh without polling.

1. Travel-club back office

Context: a tour operator runs dozens of group trips and wants every Settle Up trip ledger inside its ERP. Data/API: GET /groups/{id}/transactions + the settlement plan endpoint, exported nightly. OpenData mapping: the app becomes an authorized data source feeding a downstream system of record — the OpenData "syncs data to a backend a third party queries" pattern.

2. Shared-household accounting

Context: a property manager reconciles flatmate utilities and rent. Data/API: recurring transactions (a 2024+ Premium feature) plus per-member balances, pushed to an accounting tool via a transformer. OpenData mapping: structured transactions + balances exposed through a stable API, mirroring OpenBanking "account information" semantics for a non-bank ledger.

3. Event-organizer settlement & payouts

Context: a festival crew needs to pay everyone back once the event ends. Data/API: the minimised transfer plan ( from → to → amount ), handed to a payments provider as a payout batch, with a webhook confirming each leg. OpenData mapping: "payment initiation"-style flow built on top of computed settlement data.

4. Personal finance & budgeting aggregation

Context: a budgeting app wants a user's share of group spend alongside their bank feed. Data/API: member statistics + category analytics for the authenticated user only, normalised to one currency. OpenData mapping: consented, user-scoped data sharing — the OpenFinance "user authorizes a third party to read their data" model.

5. Compliance & audit archival

Context: an NGO must retain trip-expense evidence for grant audits. Data/API: the Excel/CSV export wrapped as an immutable monthly drop plus the change log stream. OpenData mapping: data-export portability with retention controls, aligned with GDPR data-access and record-keeping duties.

A. Authenticate & bind a group

POST /api/v1/settleup/auth
Content-Type: application/json

{
  "id_token": "<FIREBASE_ID_TOKEN>",
  "group_share_link": "https://settleup.app/g/AbC123"
}

200 OK
{
  "access_token": "<OPAQUE_TOKEN>",
  "expires_in": 3600,
  "group_id": "g_AbC123",
  "permission": "read-only"
}

B. Fetch transaction history (paged)

GET /api/v1/settleup/groups/g_AbC123/transactions
  ?from=2026-03-01&to=2026-03-31&type=expense&limit=100
Authorization: Bearer <OPAQUE_TOKEN>

200 OK
{
  "items": [
    {
      "id": "tx_91f2",
      "type": "expense",
      "purpose": "Airbnb Lisbon",
      "category": "accommodation",
      "currency": "EUR",
      "amount": 480.00,
      "amount_in_report_currency": 480.00,
      "paid_by": [{"member_id":"m_alice","amount":480.00}],
      "split": [
        {"member_id":"m_alice","weight":1},
        {"member_id":"m_bob","weight":1},
        {"member_id":"m_cara","weight":1}
      ],
      "receipt_photo": "ref://photos/tx_91f2.jpg",
      "created_at": "2026-03-12T18:04:11Z"
    }
  ],
  "next_cursor": "eyJvZmZzZXQiOjEwMH0="
}

C. Balances & minimised settlement plan

GET /api/v1/settleup/groups/g_AbC123/settlement
Authorization: Bearer <OPAQUE_TOKEN>

200 OK
{
  "report_currency": "EUR",
  "balances": [
    {"member_id":"m_alice","net": 213.34},
    {"member_id":"m_bob","net": -106.67},
    {"member_id":"m_cara","net": -106.67}
  ],
  "transfers": [
    {"from":"m_bob","to":"m_alice","amount":106.67},
    {"from":"m_cara","to":"m_alice","amount":106.67}
  ]
}

# Error handling
401  { "error": "token_expired", "retry_after": 0 }
403  { "error": "insufficient_scope", "detail": "read-only token cannot write" }
429  { "error": "rate_limited", "retry_after": 5 }

D. Change webhook (push instead of poll)

POST https://your-app.example/hooks/settleup
X-SettleUp-Signature: sha256=...

{
  "event": "transaction.updated",
  "group_id": "g_AbC123",
  "transaction_id": "tx_91f2",
  "actor_member_id": "m_alice",
  "occurred_at": "2026-05-12T09:21:40Z"
}

# Reconcile by re-pulling the affected group slice,
# then ack with 2xx within 10s or we retry with backoff.

Regulatory footing

Settle Up is built by Step Up Labs, whose team is based in the Czech Republic, so the relevant baseline is the EU General Data Protection Regulation (GDPR). The app publishes a privacy policy, names an EU representative and a Data Protection Officer, and offers an extended data export on request via privacy@settleup.io. Any integration we build respects those access and portability rights, and where the data is consumed in other regions we layer on CCPA-style consumer-data handling. Because the backend is Firebase, Google acts as a data processor — we document that sub-processor relationship in the data-flow notes we hand over.

How we work

• Authorized access only — your account, your group share link, or documented public/authorized APIs; no extraction of data you are not entitled to read.
• Data minimization — we request only the fields a scenario needs (e.g. balances without receipt photos when photos aren't required).
• Consent & access logs — every token issue and data pull is logged so you can answer a data-subject request.
• Read-only by default — write paths are added only when explicitly in scope, mirroring Settle Up's own read-only access role.
• NDA and data-processing agreement signed before any data is touched.

Deliverables checklist

• API specification (OpenAPI / Swagger) for the normalised Settle Up endpoints
• Protocol & auth flow report (Firebase ID-token / Realtime Database REST / group-link chain)
• Runnable source for auth, transaction history, balances/settlement and export wrappers (Python and Node.js)
• Webhook receiver sample and a backfill script
• Automated tests, Postman collection and API documentation
• Compliance notes (GDPR data-access mapping, Firebase sub-processor, retention guidance)

Engagement models

• Source code delivery from $300 — you receive runnable API source code plus full documentation; pay after delivery once you are satisfied.
• Pay-per-call hosted API — call our managed endpoints and pay only for the calls you make, with no upfront fee; good for teams that prefer usage-based pricing.
• Optional retainer for keeping the integration current as the app updates (e.g. new export formats, schema tweaks).

About our studio

We are an independent technical service studio focused on app interface integration and authorized API integration, with team members who have spent years in mobile apps and fintech. We take a target app name and a concrete requirement and hand back usable API or protocol-implementation source code, documentation and a test plan — built around OpenData, OpenFinance and OpenBanking patterns rather than ad-hoc scraping.

• Protocol analysis, interface refactoring, Open Data integration and third-party interface integration
• Automated data scripting and delivery of interface documentation
• Coverage across finance/banking, e-commerce and delivery, travel and mobility, and social/OTT apps
• Android and iOS, with ready-to-run Python / Node.js / Go code and CI-friendly test harnesses
• Full pipeline: protocol analysis → build → validation → compliance hand-off

Contact

To get a quote, send us the target app (Settle Up – Group Expenses) and exactly what data or flows you need. We will come back with scope, timeline and price.

Open the contact page

Two ways to engage: source-code delivery from $300 (pay on satisfaction) or pay-per-call hosted API (no upfront fee).

Engagement workflow

1. Scope confirmation — which data and flows you need (history, balances, settlement, exports, webhooks) and what you are authorized to access.
2. Protocol analysis & API design — 2–5 business days depending on complexity.
3. Build & internal validation — 3–8 business days.
4. Docs, samples and test cases — 1–2 business days.
5. Delivery — typical first drop in 5–15 business days; third-party approvals can extend timelines.

FAQ

What do you need from me to start a Settle Up integration?

Is there an official Settle Up API I can use?

How long does delivery take and what does it cost?

How do you handle privacy and compliance for group expense data?

Splitwise

The best-known shared-expense ledger, strong for ongoing roommate tracking; holds expenses, balances and settle-up records. Users who also work with Splitwise frequently want a single normalised transaction feed across both platforms.

Tricount (by bunq)

Popular in Europe for trip and group expenses with multi-currency and receipt scanning; its "tricount" objects map closely to Settle Up groups, which makes cross-export and reconciliation a common ask.

Splid

No-account, offline-first trip splitting with 150+ currencies and PDF/Excel settlement exports — the exported summaries are a natural ingestion source alongside a Settle Up feed.

Splitser

A Splitwise-style app aimed at large international groups (many members, many currencies); relevant when an organisation consolidates several group ledgers into one report.

SplitterUp

A newer entrant frequently included in "best expense splitting apps" round-ups; holds the same core shapes — expenses, participants, balances — that an integration layer needs to harmonise.

PartyTab

Positioned around no-daily-limit group tabs; another source of expense and balance data that buyers sometimes want unified with Settle Up exports.

Splitty

A bill-splitting app that appears in current comparison guides; its per-expense and settlement data fits the same OpenData mapping described above.

Cino

Takes a card-and-payment angle to shared spending; relevant when a project needs both the "split after the fact" ledger (Settle Up) and "split at payment" data in one view.

Venmo

Often mentioned alongside splitting apps for the actual money movement; pairing transfer records with a Settle Up settlement plan is a recurring reconciliation scenario.