Senior C#/.NET Engineer — AI-Driven Platform

CoStar Group; Arlington (VA); Hybrid; USD 143,000 - 187,000; Full time

Benefits offered by this job

Healthcare benefits

401K with company match

Tuition reimbursement

On-site fitness center

Job summary

CoStar Group is seeking a Senior Software Engineer (C#/.NET) in Arlington, VA, working on the Platform Development team to expand the data platform across major brands. The role emphasizes AI capabilities, telemetry, and robust distributed systems for tens of thousands of users.

You will design, implement, and integrate AI-driven automation, tools, and intelligent workflows while writing high-quality code and collaborating with Product, Research, and Data teams.

Qualifications

• Bachelor’s Degree required from an accredited university.
• 5+ years of deep .NET/C# development experience including Web API.
• Working knowledge of cloud platforms (AWS or Azure).
• Experience with RESTful web services and ASP.NET MVC.
• Experience in architecting large-scale distributed, service-oriented systems.
• Data modeling experience.
• Familiarity with LLMs, prompt engineering, or agent-based architectures.
• Experience with monitoring, telemetry, observability, or diagnostics platforms.
• Strong understanding of data quality and governance.

Responsibilities

• Build big, distributed, API-driven systems for tens of thousands of users.
• Design and implement AI-powered software solutions across CoStar brands.
• Build and integrate AI skills, agents, tools, and intelligent workflows.
• Produce robust, maintainable code using C#, .NET, SQL Server, AWS.
• Use telemetry to identify anomalies, performance bottlenecks, and issues.
• Drive software design, development standards, and code reviews.
• Develop automation to streamline research workflows and improve efficiency.
• Collaborate with Product, Research, and Data to create business value with AI.
• Evaluate emerging technologies to strengthen the platform.

Skills

C# / .NET

Web API

RESTful services

Azure / AWS

Distributed systems

Data modeling

AI awareness

Telemetry/Observability

Education

Bachelor's Degree

Tools

AWS

Azure

SQL Server

ASP.NET MVC

Job description

CoStar Group is seeking a Senior Software Engineer (C#/.NET) in Arlington, VA, working on the Platform Development team to expand the data platform across major brands. The role emphasizes AI capabilities, telemetry, and robust distributed systems for tens of thousands of users.

You will design, implement, and integrate AI-driven automation, tools, and intelligent workflows while writing high-quality code and collaborating with Product, Research, and Data teams.