Sika — money that moves the way you live

In Ghana, most everyday payments already run on mobile money, but they're split across networks and apps. Sending to someone on a different network, paying the ECG or water bill and topping up airtime can each mean a different menu, a different fee and a different receipt.

I wanted one place to do all of it, built so that the money side is trustworthy: balances that can't drift, payments that can't be applied twice, and a full trail behind every transaction.

Sika is a monorepo with a Next.js and Tailwind front end, an Express API and a PostgreSQL database. Payments come in through Paystack and SMS goes out through Arkesel.

• Double-entry ledger in the database. Every transaction is a journal entry with at least two postings that sum to zero; the database rejects any entry that doesn't balance.
• Amounts in pesewas, never decimals. Money is stored as whole numbers, so totals never pick up rounding errors.
• Append-only history. Postings are never edited or deleted. A mistake is corrected with a reversing entry, just as in a set of books.
• Safe to retry. Each payment carries an idempotency key, so if Paystack sends the same confirmation twice, the wallet is credited once.
• Built-in reconciliation. A check compares every cached balance with its postings and lists any account that disagrees. Mismatched or suspicious deposits go to a suspense account for review.

Building Sika showed me how directly accounting carries over into software. Debits, credits, reversing entries and reconciliation aren't just exam topics; they're the rules that keep a payments system honest. Writing them into the database itself means no part of the app can break them by accident.

Next: learning from beta testers and widening early access.