Principal Engineer

Principal Engineer | Cards & Payments (needed) | Sydney I $230-250k + super + bonus I Java, SpringBoot, GCP, AWS, MongoDB We're looking for a Principal Engineer to step into one of Australia's most complex card environments... High-volume, mission-critical Java/Spring ecosystem connecting to card processors (think ISO 8583 messaging, card authorisation flows, 3DS, provisioning) that underpins millions of transactions. Here's the honest breakdown of the role: ▸ 30% hands-on engineering — but not just any coding. You're setting the standard. Designing class structures that scale for future card types, demonstrating interface patterns, and showing the team what brave, efficient engineering looks like. ▸ 30% deep technical design — mono vs multi-repo decisions, microservice architecture, outbox patterns, API contract design, webhooks vs polling. You're the decision-maker for initiatives that cut across multiple platform teams. ▸ 30% platform-level leadership — assessing team capability, identifying gaps in senior engineers, mentoring future principals. Cards knowledge that will matter: → Card authorisation and decline flows → Card provisioning (tokenisation, digital wallets) → 3D Secure (3DS1/3DS2) → Card processor integration and scheme messaging → ISO 8583 / card scheme rails Strong Java without cards? Still worth a conversation, but cards + Java is the unicorn we're after. Interested? [Upgrade to PRO to see contact]