Senior Engineer

Senior Engineer Job Description

We're looking for a Senior Software Engineer to join the Keystone Squad within our Agent Workflows crew. You'll be working across a React TypeScript frontend and Ruby on Rails backend, delivering features and infrastructure used daily by thousands of agents across Australia and New Zealand. Strong TypeScript and React experience is essential. Solid backend engineering and the ability to ramp up quickly on Rails are equally important.

What you'll do

• Rails internals: Deep understanding of ActiveRecord, complex background job processing (Sidekiq), RESTful API design, and modular architectural patterns including service objects and Rails engines. Strong candidates with experience in comparable frameworks (Python/Django, Elixir/Phoenix) who can ramp up on Rails quickly are equally welcome.
• Database expertise: Query optimisation, complex joins and views, indexing strategies, query plan analysis, schema and data migration strategies; working knowledge of constraints, triggers, and stored procedures.
• Security: Rails and web security best practices including OWASP Top 10, data protection, user authentication and authorisation patterns.
• Testing: Comprehensive test coverage across unit, integration, and end to end layers using RSpec and Cypress; writes tests that build confidence, not just coverage.
• Observability: Structured logging, error handling, and APM tooling (NewRelic or equivalent); knows how to read what's happening in production.
• Frontend (primary): Deep, production proven experience with React including hooks, Context API, and state management patterns; TypeScript for type safe development; performance optimisations including memoisation, lazy loading, and code splitting.
• Infrastructure: Comfortable with AWS services, CI/CD pipelines with automated testing and deployment, Terraform basics, and secrets management best practices.

Essential

• 5+ years in software engineering with meaningful senior level experience in production systems.
• Strong TypeScript and React: you can own frontend features end to end with confidence, from component design to production monitoring.
• Solid backend engineering in Ruby on Rails, or a comparable framework (Python/Django, Elixir/Phoenix) with a genuine willingness to ramp up on Rails quickly.
• Deep PostgreSQL experience: query optimisation, indexing, migrations, and performance analysis.
• Demonstrated ability to design solutions upfront, with examples of design docs, ADRs, or architectural decisions you've led.
• A track record of improving team quality through code reviews, mentoring, documentation, or process improvement.
• Comprehensive testing practice across unit, integration, and end to end layers (Jest, RSpec, Cypress or equivalent).
• Comfortable with production observability tooling (NewRelic, CloudWatch, or equivalent).
• Strong written communication: clear PRs, tickets, and technical documentation.

Nice to have

• Prior Ruby on Rails experience in production.
• Experience with Sidekiq, Redis, and background job architecture.
• Familiarity with AWS services (RDS, SQS, S3, ECS) and Terraform.
• Experience with feature flagging systems (Flipper) and progressive rollout strategies.
• Real estate, proptech, or high volume B2B SaaS domain experience.
• Experience with API integrations across diverse payload formats (XML feeds, CRM integrations, vendor APIs).

What's In It For You?

Working at CoStar Group means you'll enjoy a culture of collaboration and innovation that attracts the best and brightest across a broad range of disciplines. We offer generous compensation and performance based incentives. You will also enjoy an outstanding working environment with extra days of annual leave, leadership development programs, LinkedIn Learning, Perkbox discounts and much more.

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.