Software Engineer I (C#/.NET)
About The Position
CoStar Group is hiring a Software Engineer I for its Platform Development team in Arlington, Virginia. The role supports the data platform used by CoStar Group brands, including CoStar Suite, LoopNet, Homes.com, and Apartments.com. The engineer will develop and expand distributed, API-driven systems and build software with a strong understanding of the business it serves. The position focuses on applying artificial intelligence to software delivery, platform observability, research and business workflows, product experiences, and enterprise data quality. The engineer will develop and integrate AI-powered solutions, agents, tools, and workflows into internal systems and customer-facing applications, and use telemetry and AI models to improve diagnostics, reliability, and operational efficiency. The role involves learning and applying software development standards, participating in code reviews, and evaluating emerging technologies. The position is based in Arlington, VA, with employees working in the office Monday through Thursday and from home on Friday. CoStar Group describes a collaborative and innovative culture and offers compensation and performance-based incentives, professional and academic development opportunities, and a range of benefits.
Requirements
- Bachelor's degree from an accredited, not-for-profit, in-person university or college.
- A track record of commitment to prior employers.
- At least 3 years of deep .NET (C#) development experience, including cross-platform communication technologies such as Web API.
- Working knowledge and experience with cloud-based platforms such as AWS or Azure.
- Experience with RESTful web services.
- Experience architecting, designing, and building distributed, service-oriented systems and web applications in an agile environment.
- Data modeling experience.
- Familiarity with large language models (LLMs), 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.
Nice To Haves
- Strong communication skills with business and technical partners.
- SQL and database development knowledge.
- Familiarity with AWS PaaS services such as Lambda, DynamoDB, and SQS.
- Data modeling experience across conceptual, logical, and physical designs.
- Experience implementing AI agents, workflow automation platforms, or intelligent search solutions.
- Experience applying AI-assisted software development practices to improve engineering productivity and code quality.
Responsibilities
- Build large, distributed, API-driven systems for tens of thousands of users.
- Design and implement AI-powered software solutions to enhance customer experiences, platform intelligence, and product capabilities across CoStar brands.
- Build and integrate AI skills, agents, tools, and intelligent workflows into internal systems and customer-facing applications.
- Produce robust, efficient, and maintainable code using tools including C#, .NET Framework, SQL Server, AWS, and Claude Code.
- Use AI models to improve monitoring, replayability, observability, and diagnostics, improving reliability, problem resolution, and operational risk.
- Implement telemetry-driven solutions to identify anomalies, performance bottlenecks, and potential customer-impacting issues.
- Learn software design and development standards and participate in code reviews.
- Build intelligent automation solutions to streamline research workflows, improve information discovery, and increase operational efficiency.
- Evaluate emerging technologies, trends, and best practices for opportunities to strengthen CoStar's technology platform and development practices.
Benefits
- Generous compensation and performance-based incentives.
- Internal training and tuition reimbursement.
- Medical, vision, dental, and prescription drug coverage.
- Life, legal, and supplementary insurance.
- Virtual and in-person mental health counseling services for individuals and families.
- Commuter and parking benefits.
- 401(k) retirement plan with matching contributions.
- Employee stock purchase plan.
- Paid time off.
- On-site fitness center and/or reimbursed fitness center membership costs, depending on location.
- Access to Employee Resource Groups.
- Complimentary gourmet coffee, tea, hot chocolate, fresh fruit, and other healthy snacks.
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What This Job Offers
Job Type
Full-time
Career Level
Entry Level
