Senior Full Stack Engineer – Kotlin / Spring Boot / React

Sydney | Hybrid | 6-Month Day Rate Contract + Likely Extension

We’re partnering with a major Australian enterprise going through significant technology transformation, with a number of greenfield initiatives on the roadmap.

We’re looking for a strong backend-leaning Full Stack Engineer who enjoys solving complex problems, owning outcomes and working across the stack when needed.

The prospect

You’ll work within a modern product engineering environment, building and evolving scalable applications while contributing to new greenfield development.

The backend is centred around Kotlin and Spring Boot, but this isn’t a purely backend role. You’ll need enough frontend capability to comfortably work across modern JavaScript applications, with TypeScript and React particularly relevant.

There’s also a strong focus on how engineers are harnessing AI tooling to improve the way they build software. We’re keen to meet developers already using tools such as Claude Code, Cursor,



Copilot or coding agents to accelerate development, testing, debugging and delivery.

What we’re looking for
Strong Kotlin / Java and Spring Boot engineering experience
Genuine full stack capability, with a backend bias
Exposure to JavaScript, TypeScript and/or React
Experience building APIs, microservices and distributed applications
Good exposure to contemporary AWS or GCP cloud environments
Engineers actively incorporating AI tooling into their development workflows
Strong problem-solving skills and the ability to take ownership from idea through to production
Comfortable working within up-to-date CI/CD and product engineering environments

Initial 6-month day rate contract with a strong likelihood of extension.

If you’re a hands-on engineer who enjoys difficult technical problems, modern technology and the opportunity to contribute to genuine greenfield development, I’d be keen to hear from you.

📌 Staff Engineer Spring Boot Kotlin Gcp (Sydney)
🏢 The Onset
📍 Sydney