Senior Software Engineer

Costar Group; Sydney; On-site; AUD 140,000 - 190,000; Full time

Job summary

Domain is seeking a Senior Software Engineer to own the full lifecycle of medium-sized projects, from design through deployment, in a high-scale search platform environment. You will contribute to OpenSearch-backed APIs powering millions of property searches.

You will collaborate with product owners and tech leads to ensure security, performance, and reliability at scale, mentoring junior engineers and driving improvements across domains.

Qualifications

• The candidate holds a degree in computer science or software engineering.
• Strong experience with C# / .NET and OpenSearch/Elasticsearch.
• Experience designing scalable backend services for high-traffic environments.
• Familiarity with one or more Cloud platforms (AWS, Azure, GCP).
• Practical knowledge of CI/CD and infrastructure-as-code.

Responsibilities

• Owns full lifecycle of medium-sized software projects.
• Write, review, and maintain production-ready code and docs.
• Address security vulnerabilities and perform code reviews.
• Collaborate with product owners to align with business needs.
• Improve system health and reduce technical debt.

Skills

C# / .NET

Distributed systems

Cloud platforms (AWS/Azure/GCP)

DevOps / CI/CD

Security best practices

Performance optimization

Cross-functional collaboration

Mentoring juniors

Education

Degree in Computer Science / Software Engineering

Tools

Elasticsearch/OpenSearch

AWS/ECS/EKS

Job description

The Senior Engineer is pivotal in supporting the delivery of our Domain Strategy by driving innovation and ensuring the development of high-quality software solutions. They are responsible for the entire lifecycle of medium-sized projects: engineering design, development, test, production, and deployment and subsequent fixes and improvements.

The Search Platform squad owns Domain's search and discovery layer - services that power how millions of users find property across residential and commercial markets every day. We are responsible for the high-performance, OpenSearch-backed APIs at the heart of the Domain experience, focusing on relevance, reliability, and scale under heavy production load. As Domain's technology landscape evolves, our squad plays a key role in shaping how discovery integrates with CoStar's global platform, while continuing to own the critical-path services behind every property search on Domain.

What you'll do

• Responsible for the entire lifecycle of medium-sized projects: engineering design, development, test, production, and deployment and subsequent fixes and improvements.
• Finds solutions to unsolved, loosely-defined, highly-technical problems.
• Consistently writes, co-writes, and reviews documentation and production-ready code that is clear, concise, tested, and easily understood by others.
• Proficient in multiple languages, frameworks, and tools.
• Quick and effective in identifying and resolving issues, balancing trade-offs between speed, quality, and technical debt.
• Approaches work with a security lens and actively looks for security vulnerabilities both in code and when providing code reviews.
• Understands the big picture and system-wide impact, aligning with and contributes to domain wide architecture, security and technology standards
• Designs solutions with scalability and future needs in mind.
• Collaborates with Product Owners to ensure that solutions are aligned with business and customer needs.
• Optimises for performance, maintainability, and security, actively looks for security vulnerabilities both in code and when providing code reviews.
• Contribute to the System Health and Tech debt backlog for their respective owned service.
• Collaborate with Lead Engineers and Tech Leads on improving process and system change.

• Degree in Computer Science / Software Engineering or related field
• Strong experience in C# / .NET, Elastic Search or Open Search for distributed backend services
• Experience designing software solutions for scale
• Experience with high traffic customer-facing services
• Experience working with one of the common Cloud Platforms such as AWS, Azure or GCP
• DevOps practices, CI/CD, and infrastructure-as-code
• Familiar with Cloud Design patterns
• Familiar with modern Application Security Practices (OWASP)
• Understanding of shift-left testing and how to implement it in practice
• Experience with microservices and event-driven architectures
• Experience working with Tech leads to optimise engineering practices and processes
• Experience mentoring more junior engineers
• Experience working in cross-functional teams (Product, Design and Tech)

Nice to have

• Hands on experience with AWS (ECS/EKS, Bedrock, IAM, networking)
• Experience with AI-assisted engineering workflows
• Experience building production AI/LLM systems
• TypeScript / Node.js for AWS Lambda and infrastructure-as-code (CDK)
• AWS (or other Cloud Platform) Certification

What's In It For You?

About Domain (part of the CoStar Group)

Domain is a leading property technology and services marketplace that is home to one of the largest portfolios of property brands in Australia, including the Domain, Allhomes and Commercial Real Estate (CRE) platforms. In 2025, Domain became part of CoStar Group - a global leader in commercial real estate information, analytics, online marketplaces and 3D digital twin technology. We are dedicated to digitising the world's real estate, empowering all people to discover properties, insights, and connections that improve their businesses and lives.

Equity, Diversity & Inclusion

Domain is enthusiastically and unapologetically committed to fostering an equitable, inclusive work culture which reflects our customers and communities. We are proactively looking for candidates from all lived experiences, including people with disability, and people of all ages, ethnicities, cultures (including Aboriginal and Torres Strait Islander Peoples), faiths, sexual orientations, and gender identities (including trans and non-binary people).

We are committed to providing an equitable recruitment process for people with disability. If you require adjustments during the process we're here to support. If you wish to receive this job advertisement in an accessible format, or have a confidential chat about workplace adjustments, please contact our Equity, Diversity and Inclusion team at or leave a message on and we will get back to you.

CoStar Group is an Equal Employment Opportunity Employer; we maintain a drug-free workplace and perform pre-employment substance abuse testing

Senior Software Engineer • 2000, NSW, AU