Software · Open source · 2026
Danube Bank
An open-source banking system you can run in minutes: a customer app, a separate operator console, a double-entry ledger, cards, loans and KYC on FastAPI and MySQL.
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- 2
- applications: customer and operator
- 12
- tables in one MySQL schema
- 14
- automated tests on the ledger
A complete banking platform that runs on your machine with Docker and Python: online banking for customers on one port, the operator console on another, and one MySQL database underneath. It exists as a learning and demo reference, not as a bank; there is no real money and no real customer data.
What we built
- Customer app: accounts, instant transfers, saved beneficiaries, standing orders, statements and CSV export
- Virtual cards with Luhn-valid numbers, encrypted card numbers, hashed PINs, freeze and daily limits
- Loans with live quotes, amortisation schedules, instalments and early repayment
- Operator console: create and lock customers, KYC decisions, account adjustments, ledger search and reversal, card issuing, loan approval
- Every balance lives in a double-entry ledger, and transfers are row-locked inside a database transaction
- A searchable audit trail of every operator action, and a database browser with SQL console and backup
Every screen and button is backed by real functionality: no mock APIs, no fake charts, no disabled controls. Fourteen automated tests check the ledger invariants. MIT licensed, so it can serve as the starting point for a real project.