Principal Software Engineer

About Fat Zebra

At Fat Zebra, we simplify payments so merchants and platforms can scale with confidence. Our flexible, secure, and scalable payments platform supports over 100,000 merchants across Australia and New Zealand, helping them navigate the complexity of the payments ecosystem so they can focus on what matters most growing their business.

We simplify the payments process so that our customers can focus on what matters most: growing their businesses. Our innovative technology and expert support help them confidently navigate the complexity of the payment’s ecosystem.

About the Position

We need a hands-on technical leader to own and scale a critical open banking system in production. You will design, build, and deliver, working directly in the code while raising the capability of the team around you.

You're joining a 3-person full stack team. The platform handles millions of API calls/week across 50+ enterprise customers, scaling to 5x over 12 months. We need to scale data retrieval, improve async processing and observability to support our growth.

The stack: Kotlin/Java, Spring Boot, MySQL, AWS (for all our infrastructure - e.g. ECS Fargate, Lambda, CloudFormation, messaging/eventing, Aurora/DynamoDB), OAuth2/OIDC, TypeScript, React.

Position Responsibilities

• ·Be hands on - write and review production code, tackle concurrency, data consistency, and performance. Set the engineering standard through code, not docs
• Own and execute a scaling plan - assess bottlenecks, define an opinionated technical plan, break it into milestones, and execute it end-to-end with the team.
• Own platform reliability and performance - define what good looks like, lead the team to get there. Improve async/event-driven patterns, idempotency, safe retries, and database efficiency improvements
• Multiply the team - uplevel the team’s engineers through pairing, code reviews, and technical guidance.
• Maintain CDR compliance - contribute to audits, security assessments, and regulatory reporting in a government-regulated data environment
• Leverage AI for productivity - use AI tools to accelerate development, improve quality, and introduce AI-assisted workflows (test generation, code review, documentation)
• Introduce AI-driven capabilities - identify practical opportunities such as intelligent alerting, anomaly detection, and runbook automation; design safe, auditable, deterministic AI interactions
• Drive pragmatic decisions - make clear trade-offs between speed and robustness, simplicity and flexibility; avoid over-engineering. Shape how the broader team thinks about building software, not just what gets shipped

Skills & Experience

• Strong production experience building and scaling backend systems
• Deep knowledge of Java/Kotlin, Spring Boot, REST and/or event-driven architectures
• AWS experience with understanding of working with RDS, ECS, SQS in production
• Distributed systems fundamentals, database performance and a strong focus on async patterns
• Strong understanding of modern authentication and authorisation patterns, including OAuth2/OIDC and JWT
• Proven ability to turn ambiguous problems into delivered solutions
• mTLS experience - required for CDR; production experience strongly preferred
• Practical experience with AI tools for engineering productivity
• Ability to evaluate AI value vs risk
• Understanding of LLM limitations and data privacy concerns in AI usage

Ideally, you possess;

•  AWS networking and connectivity (e.g. VPC design, subnets, routing, security groups/NACLs, VPC endpoints/PrivateLink, Transit Gateway, VPN/Direct Connect, ALB/NLB, service-to-service connectivity

• Infrastructure as code (e.g. Terraform, CDK or CloudFormation)

• Idempotency, transaction integrity, API design for external consumers

• Experience in regulated environments (CDR, Open Banking, or equivalent)

What This Role Is Not

• Not an ivory-tower architect role
• Not a people manager role
• Not "AI for the sake of AI"
• Not a "code everything yourself" role

This is a high-impact role at the core of a regulated fintech platform. The scaling work you deliver and the standards you set will shape how this team operates for years.

For a confidential discussion, please contact Fat Zebra’s Talent Manager - Rose Maugeri on 0409236061.