Senior Full Stack Engineer

Senior Full Stack Engineer

Job Description

CoStar Group (NASDAQ: CSGP) is a leading global provider of commercial and residential real estate information, analytics, and online marketplaces. Included in the S&P 500 Index, CoStar Group is on a mission to digitize the world’s real estate, empowering all people to discover properties, insights and connections that improve their businesses and lives. We have been living and breathing the world of real estate information and online marketplaces for over 35 years, giving us the perspective to create truly unique and valuable offerings to our customers.

We’ve continually refined, transformed and perfected our approach to our business, creating a language that has become standard in our industry, for our customers, and even our competitors. We continue that effort today and are always working to improve and drive innovation. This is how we deliver for our customers, our employees, and investors. By equipping the brightest minds with the best resources available, we provide an invaluable edge in real estate.

As a Senior Software Engineer on the Platform Development team, you will play a key role in expanding the data platform that supports all of CoStar Group’s largest brands including CoStar Suite, Loop Net,  and

• Build big, distributed, API-driven systems for tens of thousands of users.
• Build and integrate AI skills, agents, tools, and intelligent workflows into internal systems and customer-facing applications across CoStar brands, improving platform intelligence and unlocking new product capabilities.
• Produce code that is robust, efficient, and maintainable; our primary tools are Type Script, C#, .NET, SQL Server, AWS.
• Build and maintain customer-facing and internal web applications using React/Type Script.
• Utilize AI models to enhance monitoring, replayability, observability, and diagnostic capabilities to improve system reliability, accelerate problem resolution, and reduce operational risk.
• Drive and lead software design, development standards, and code review practices.
• Collaborate with Product, Research, and Data teams to identify opportunities where AI-driven workflows and automation can create business value and improve decision-making.
• This position is located in Arlington, VA and is in office Monday through Thursday with work from home on Friday.

• Bachelor’s Degree required from an accredited, not for profit, in person, university or college.
• A track record of commitment to prior employers.
• 3+ years of deep .NET development (C#) development experience such as web APIs, background services, and developing and publishing shared packages.
• 5+ years of experience with Type Script and modern frontend and backend JS tooling (e.g. Node, Vite, React, etc.).
• Experience with Infrastructure as Code (IaC) tools such as Terraform.
• Working knowledge and experience with cloud-based platforms (AWS or Azure).
• Experience in architecting, designing, and building large-scale distributed, service-oriented systems and web applications in an agile environment.
• Familiarity with using large language models (LLMs), context engineering, or agent-based architectures.
• Experience working with monitoring, telemetry, observability, or automated diagnostics platforms.
• Strong understanding of data quality principles, data governance concepts, and data-centric application design.

• Strong communication skills (to both business and technical partners).
• Experience with React Router Framework and Effect.
• SQL and database development knowledge.
• Experience using observability and APM platforms like Datadog.
• Familiarity with services such as Kafka, DynamoDB, and SQS.
• Experience with deploying to Kubernetes, EKS, and ECS.
• Data modeling experience from conceptual, logical, and physical designs.
• Experience implementing MCP clients and servers, workflow automation platforms, or intelligent search solutions.
• Experience applying AI-assisted software development practices to improve engineering productivity and code quality.

When you join CoStar Group, you’ll experience a collaborative and innovative culture working…