Mid Backend Engineer (BFF/Kotlin/Java/Spring)

Hello, we’re Bilue - a leading design and development agency specialising in mobile, cloud, web, and emerging technologies.

Bilue was founded by Cameron Barrie, an app developer with a vision to help Australian companies design and deliver cutting-edge digital experiences. What began in Cam’s living room has grown into a thriving company with a team of 50+, and offices in Sydney and Melbourne. For more than 14 years, we’ve partnered with some of Australia’s top brands to create innovative, human-centred digital solutions.

About the Role

As a Back-end Engineer (BFF) at Bilue, you will take ownership of the Backend-for-Frontend (BFF) layer that powers our clients' mobile applications. You’ll be responsible for developing and maintaining backend services tailored specifically to the needs of mobile front-ends, with a focus on performance, usability, and scalability.

This role is ideal for someone with solid experience in Kotlin (or Java with a willingness to transition) and a good understanding of Spring Boot. Familiarity with the Server-Driven UI pattern is a strong plus.

Key Responsibilities

• Design, build, and maintain BFF services that serve our mobile apps with optimised, tailored APIs
• Collaborate closely with mobile engineers, designers, and product managers to deliver seamless user experiences
• Use Kotlin (preferred) or Java with Spring Boot to develop scalable backend services
• Implement and maintain patterns for feature toggles, A/B testing, and dynamic UI rendering via server-driven approaches
• Ensure strong API versioning, documentation, and backward compatibility for mobile consumption
• Write clean, testable, and well-documented code that follows best practices
• Identify bottlenecks, debug performance issues, and propose reliable solutions
• Contribute to discussions on API design, system architecture, and scalability

About You

You're a backend engineer with a passion for building backend systems that power rich mobile experiences. You’re excited about collaboration, scalable systems, and high-quality APIs. You're proactive, technically curious, and enjoy working in a fast-moving, cross-functional team.

• 3–5 years of experience in backend development with Kotlin (preferred) or Java
• Strong experience with Spring Boot and RESTful API development
• Understanding of mobile app requirements and the role of BFFs in supporting cross-platform experiences
• Familiarity with CI/CD tools and modern development workflows (Git, GitHub/GitLab, Jenkins, etc.)
• Solid understanding of API security, caching strategies, and data serialisation formats (JSON, Protobuf)
• Excellent collaboration and communication skills, with experience working in agile teams

Bonus Points For

• Experience with Server-Driven UI patterns and dynamic UI delivery
• Exposure to GraphQL or similar query-driven API designs
• Familiarity with feature flags, remote configuration tools, or A/B testing platforms
• Knowledge of mobile development (Android or iOS) and how mobile apps consume APIs
• Experience with containerization (Docker), orchestration (Kubernetes), and cloud platforms (AWS, GCP, Azure)

Life at Bilue

• Client-focused: We are dedicated to delivering exceptional value to our clients while supporting each other to achieve collective success.
• Flexible work: We offer 1-2 days per week in the office, balancing flexibility with the expectation that you'll go the extra mile for our clients when needed.
• Professional development: We’re committed to your personal and professional growth, offering continuous learning through Go1 (which provides unlimited access to a wide range of courses), along with support from our dedicated internal performance coach.
• Annual events: We organise annual events to foster in-person connection and team collaboration.
• Flat structure: We operate with a flat structure, where our casual, approachable executive leadership team (ELT) ensures everyone’s voice is heard.
• Internal communities: We build and nurture internal communities for knowledge sharing and collaboration, keeping everyone connected and informed.

Bilue = Big + Blue Ocean. Are you ready to set sail? Apply now!

NB. This is a full-time position based in Sydney. To be considered, candidates must have unrestricted working rights in Australia.

We believe that having balanced and diverse teams is fundamental to our success. We welcome applicants of all backgrounds and experiences and are committed to fostering an inclusive environment where everyone feels respected and valued. We do not discriminate based on race, religion, national origin, gender identity or expression, age, sexual orientation, marital status, neurodiversity or disability status. 

We are a 2024 Circle Back Initiative Employer – we commit to respond to every applicant.