I replaced spreadsheets with a Finance OS: here's the architecture

Running an agency across two countries means two legal entities, two bank accounts, two tax systems, and twice the accounting headaches. For the first year, I managed it all in spreadsheets. Then I stopped.

The problem

Boring Commerce operates as an LLP in India and an LLC in the US. Every month I need to track: revenue from each client in both INR and USD, expenses across both entities, GST obligations in India, contractor payments, salary disbursements, and payment gateway reconciliation.

In a spreadsheet, this was multiple tabs, manual data entry, constant formula errors, and a monthly panic before the accountant's deadline.

What I built

The Finance OS is a module inside our agency dashboard. It syncs with Zoho Books (our accounting software) via API, auto-categorizes transactions, tracks compliance deadlines, and gives me a real-time view of cash position across both entities.

Key components:

• Full database schema: transactions, invoices, bills, journal entries, categories, rules, compliance deadlines, salary records, payment reconciliation
• Zoho Books sync: OAuth2 integration with two-factor authentication. Bi-directional: reads transactions in, posts invoices out.
• Auto-categorization engine: learns from historical patterns. After training on a few hundred transactions, it correctly categorizes the vast majority of new ones automatically.
• Compliance calendar: every Indian tax deadline (GST, TDS, advance tax, annual filings) with countdown timers and Slack alerts. Missing a filing deadline means penalties, and the system makes sure that never happens.
• Payment reconciliation: settlement imports with automatic reference matching against invoices. Catches missed payments.
• Dashboard pages: overview, transactions, categorization, invoices, bills, journals, P&L, receivables, payables, salary, GST, TDS, compliance, reconciliation health, forecast.

Was it worth building?

Monthly accounting used to take two full days. Now it takes about two hours, mostly spent reviewing what the system auto-categorized and approving edge cases.

The compliance calendar alone has saved me from missed deadlines multiple times. The system paid for its development time within the first quarter.