Senior Software Engineer (C#/.NET)
CoStar GroupBase Salary
$143k - $187k/yr
Responsibilities
- Build large-scale, distributed, API-driven systems for tens of thousands of users.
- Design and implement AI-powered software solutions, AI agents, skills, tools, and intelligent workflows.
- Develop robust, efficient, and maintainable software using C#, .NET Framework, SQL Server, and AWS.
- Use AI models and telemetry to improve monitoring, observability, diagnostics, reliability, and operational risk management.
- Implement solutions that identify anomalies, performance bottlenecks, and potential customer-impacting issues.
- Lead software design, development standards, and code reviews.
- Build intelligent automation for research workflows, information discovery, and operational efficiency.
- Collaborate with Product, Research, and Data teams to identify AI-driven business opportunities.
- Evaluate emerging technologies, trends, and best practices for the technology platform.
Requirements
- Bachelor’s degree from an accredited, not-for-profit, in-person university or college.
- 5+ years of deep .NET and C# development experience, including Web API or similar cross-platform communication technologies.
- Experience with cloud platforms such as AWS or Azure.
- Experience with RESTful web services and ASP.NET MVC.
- Experience architecting, designing, and building large-scale distributed, service-oriented systems and web applications.
- Data modeling experience, including conceptual, logical, and physical designs preferred.
- Familiarity with large language models, prompt engineering, or agent-based architectures.
- Experience with monitoring, telemetry, observability, or automated diagnostics platforms.
- Strong understanding of data quality principles, data governance concepts, and data-centric application design.
- SQL and database development knowledge.
- Familiarity with AWS Lambda, DynamoDB, and SQS preferred.
- Experience implementing AI agents, workflow automation platforms, or intelligent search solutions preferred.
- Experience applying AI-assisted software development practices preferred.
- Strong communication skills with business and technical partners.
- A track record of commitment to prior employers.
Benefits
- Comprehensive medical, vision, dental, prescription drug, life, legal, and supplementary insurance.
- Virtual and in-person mental health counseling for individuals and families.
- Commuter and parking benefits.
- 401(k) retirement plan with matching contributions.
- Employee stock purchase plan and paid time off.
- Tuition reimbursement, internal training, and professional and academic growth opportunities.
- On-site fitness center or reimbursed fitness center membership costs, depending on location.
- Employee Resource Groups, complimentary beverages, fresh fruit, and healthy snacks.
- Located in Arlington, VA; in-office Monday through Thursday with work from home on Friday.
Categories
About CoStar Group
CoStar Group (NASDAQ: CSGP) is a global leader in commercial real estate information, analytics, online marketplaces, and 3D digital twin technology. Founded in 1986, CoStar Group is dedicated to digitizing the world’s real estate, empowering all people to discover properties, insights, and connections that improve their businesses and lives. CoStar Group’s major brands include CoStar, a leading global provider of commercial real estate data, analytics, and news; LoopNet, the most trafficked commercial real estate marketplace; Apartments.com, the leading platform for apartment rentals; Homes.com, the fastest-growing residential real estate marketplace; and Domain, one of Australia’s leading property marketplaces. CoStar Group’s industry-leading brands also include Matterport, a leading spatial data company whose platform turns buildings into data to make every space more valuable and accessible, STR, a global leader in hospitality data and benchmarking; Ten-X, an online platform for commercial real estate auctions and negotiated bids; and OnTheMarket, a leading residential property portal in the United Kingdom. CoStar Group’s websites attracted over 143 million average monthly unique visitors in the third quarter of 2025, serving clients around the world. Headquartered in Arlington, Virginia, CoStar Group is committed to transforming the real estate industry through innovative technology and comprehensive market intelligence. From time to time, we plan to utilize our corporate website as a channel of distribution for material company information. For more information, visit CoStarGroup.com.