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. At this level, we expect you to own more than your ticket. That means thinking about design before writing code, building tests that give you and your team genuine confidence, monitoring production after you ship, and making the engineers around you better. You are not just a contributor; you are a force multiplier. 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 memoization, 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 toproduction monitoring Solid backend engineering in Ruby on Rails, or a comparable framework (Python/Django, Elix ir/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 you generous compensation and performance-based incentives. As well as having an outstanding working environment,