Backend Engineer - Crypto and Payments

About the role

We are looking for a hands-on Core Backend Engineer with strong financial-systems and database experience to build Project White's ledger, posting, reconciliation, and financial-control capabilities. You will build systems that calculate balances, record movements of value, prevent duplicate or missing postings, and explain each financial state change.

What you'll do

• Build and improve an event-sourced, append-only double-entry ledger and its account, journal, posting, balance, hold, fee, FX, and adjustment models
• Implement posting rules and invariants that keep journals balanced, prevent unauthorised value creation or loss, and provide a clear audit trail
• Build transaction-processing flows for authorisation, holds, capture, settlement, reversals, refunds, chargebacks, expiry, corrections, and controlled manual adjustments
• Apply idempotency, deduplication, sequencing, and concurrency controls to payment, card, custody, and blockchain events that may arrive late or more than once
• Build reconciliation controls across the managed CASP ledger, Fireblocks, on-chain data, fiat ramps, card processing, treasury and accounting systems

What you need

• 5–9 yrs of experience
• SQL
• Java
• Python
• PostgreSQL
• AWS
• Kafka
• Any graduate

Good to have

• Reconciliation
• Treasury
• General ledger
• Incident response
• Root cause analysis
• Data warehousing