Flo

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Overview

Flo is a full-stack personal finance management (PFM) app built for the Australian market, designed around real Open Banking (Consumer Data Right) integration. It handles bank connection and transaction sync, a dashboard with spending insights, transaction management, custom categories, and manual cash account tracking - the same feature set and architecture expected of a production PFM product.

I built the entire product solo across 43 completed, issue-tracked milestones, from initial project scaffolding through to a fully working dashboard and transaction system.

My Role

Problem

Personal finance apps are only useful if they can reliably connect to real bank accounts - pulling in transactions, deriving balances, and giving people an accurate, real-time view of their spending. In Australia, that means integrating with the Consumer Data Right (CDR), the regulatory framework behind Open Banking.

To pull live bank data, a provider needs either direct accreditation from the ACCC, or to operate as a "Representative" under an already-accredited provider (an Accredited Data Recipient, or ADR - Basiq and Frollo are examples). The Representative pathway is meant to be the accessible route for smaller developers, but in practice both providers reserve it for established businesses with a commercial relationship, not individual developers building a portfolio project. I approached both and was declined on that basis.

Solution

Rather than treat the regulatory wall as a dead end, I built Flo to the same standard it would need for a real launch, and pointed the one component that legally required enterprise accreditation - the live bank connection - at Basiq's sandbox environment instead.

Everything upstream of that connection is production-grade:

• A real OAuth-style Open Banking consent and auth flow
• Real transaction sync with pagination and idempotent upserts (no duplicate transactions on repeated syncs)
• Real balance derivation, scoped only to account types where it stays accurate
• A 15-minute cron-based background sync, matching how a live integration would run

The result is a fully working app that behaves exactly as it would in production, just connected to test institutions instead of real banks.

Application Features

Authentication

• Sign up, sign in, and OAuth via Clerk
• Email verification and password reset flows

Bank Connection

• Guided multi-step onboarding: select institution, consent, mobile verification, connect, sync
• Basiq-powered Open Banking auth and 90-day historical transaction fetch
• Automatic 15-minute background sync via cron

Dashboard

• Summary stat cards (income, expenses, net savings)
• Cashflow trend chart with Detailed/Summary toggle and period navigation
• Spending-by-category donut chart
• Connected accounts and recent transactions at a glance

Transactions

• Searchable, filterable transaction list (date range, account, category, type)
• Detail panel with inline editing, category reassignment, and exclude-from-budget toggle

Accounts

• Connect, disconnect, and sync individual accounts
• Account detail panel with a 30-day derived balance history (transaction/savings accounts only)

Categories

• System-defined categories plus fully custom user-defined categories with icon and color pickers

Manual Accounts

• Cash account tracking alongside connected bank accounts, with full add/edit/delete support

Technical Highlights

Timezone-Correct Data Architecture

• Every request carries an x-timezone header rather than storing timezone in the database, where it would go stale
• Clear separation between UTC boundary helpers (used for Prisma queries) and display/grouping helpers (used for chart bucketing)

Backend-Grouped Analytics

• Cashflow chart summaries (weekly/fortnightly/monthly) are grouped on the backend rather than shipping raw daily records to the client, keeping payloads small and chart rendering fast

Idempotent Sync Pipeline

• Transaction sync upserts on a unique Basiq transaction ID, so overlapping or repeated syncs never create duplicate records
• Compound-unique constraints involving nullable fields handled with explicit findFirst + create/update logic, since Prisma's upsert doesn't support nullable fields in compound uniques

Derived Balance History

• Open Banking data doesn't include historical balance snapshots, so balance history is derived by walking backwards from the current balance through stored transactions
• Scoped to transaction/savings accounts only - credit cards, mortgages, and loans are excluded, since large repayments distort the derived trend

What This Project Demonstrates

• Solo ownership of a complete, multi-milestone product - from data model to polished UI
• Working with a real third-party financial API, including its auth quirks, pagination, and idempotency requirements
• Timezone-correct data handling across a full-stack application
• Backend-driven analytics design for fast, chart-ready aggregation
• Recognizing and adapting to a regulatory constraint outside my control, without compromising the quality of the engineering

Impact

Flo is a complete, production-architected PFM application built solo, covering authentication, real Open Banking integration patterns, a full dashboard, transaction management, and custom categorization. Live bank data access was blocked by CDR accreditation requirements reserved for established businesses - not a gap in the engineering - and the project stands as a demonstration of shipping real-world financial software end to end.

Links

• GitHub Repository