Software Engineer (C#/.NET)
About The Position
As a 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, LoopNet, Homes.com and Apartments.com. You will deeply understand what drives the business for which you are building software. We firmly believe that what separates a good developer from a great one is a deep understanding of the business that they are supporting. CoStar is investing heavily in artificial intelligence to accelerate software delivery, improve platform observability, automate research and business workflows, enhance product experiences through intelligent agents and skills, and improve data quality across enterprise systems. Successful candidates will demonstrate a willingness to learn, adopt, and apply AI technologies responsibly to solve complex business and engineering challenges. This position is located in Arlington, VA and is in office Monday through Thursday with work from home on Friday.
Requirements
- 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 including cross platform communication technologies such as Web API.
- Working knowledge and experience with cloud-based platforms (AWS or Azure).
- Experience with RESTful web services and ASP.NET MVC.
- Experience in architecting, designing, and building large-scale 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 working 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 (to both business and technical partners).
- SQL and database development knowledge.
- Familiarity with AWS PaaS services such as Lambda, DynamoDB, and SQS.
- Data modeling experience from 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 big, distributed, API-driven systems for tens of thousands of users.
- Design and implement AI-powered software solutions that enhance the customer experience, improve platform intelligence, and unlock new product capabilities across CoStar brands.
- Build and integrate AI skills, agents, tools, and intelligent workflows into internal systems and customer-facing applications.
- Produce bullet-proof code that is robust, efficient, and maintainable; our primary tools are C#, .NET Framework, SQL Server, AWS.
- Utilize AI models to enhance monitoring, replayability, observability, and diagnostic capabilities to improve system reliability, accelerate problem resolution, and reduce operational risk.
- Implement telemetry-driven solutions that proactively identify anomalies, performance bottlenecks, and potential customer-impacting issues.
- Drive and lead software design, development standards, and code reviews.
- Build intelligent automation solutions that streamline research workflows, improve information discovery, and increase operational efficiency across business functions.
- Collaborate with Product, Research, and Data teams to identify opportunities where AI-driven automation can create business value and improve decision-making.
- Continually evaluate emerging technologies to identify opportunities, trends, and best practices that can be leveraged to strengthen CoStar’s technology platform and development practices.
Benefits
- Comprehensive healthcare coverage: Medical / Vision / Dental / Prescription Drug
- Life, legal, and supplementary insurance
- Virtual and in person mental health counseling services for individuals and family
- Commuter and parking benefits
- 401(K) retirement plan with matching contributions
- Employee stock purchase plan
- Paid time off
- Tuition reimbursement
- On-site fitness center and/or reimbursed fitness center membership costs (location dependent)
- Access to CoStar Group’s 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
Mid Level
