# Senior Software Engineer (C#/.NET) at CoStar Group

- Company: CoStar Group
- Company website: https://www.costargroup.com
- Type: Startups
- Level: Senior
- Location: US-VA Arlington
- Work setup: On-site
- Pay: $143K to $187K base salary per year (USD)
- Posted: 2026-09-23
- Apply by: 2026-11-07
- Apply: https://costar.wd1.myworkdayjobs.com/en-US/CoStarCareers/job/US-VA-Arlington/Senior-Software-Engineer--C--NET-_R39330
- Page: https://www.1752.vc/careers/jobs/costar-group-senior-software-engineer-c-net/

## About the role

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, 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.

## What they're looking for

- 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