Software Engineer I (C#/.NET) – AI-Driven Platform

CoStar Realty Information, Inc.; Arlington (VA); Hybrid; USD 108,000 - 154,000; Full time

Benefits offered by this job

Comprehensive healthcare coverage

401(K) retirement plan with matching

Employee stock purchase plan

Paid time off

Tuition reimbursement

On-site fitness center

Employee Resource Groups

Gourmet snacks

Job summary

CoStar Group, Inc. in Arlington, VA is seeking a Software Engineer I (C#/.NET) to contribute to the Platform Development team.

You will build distributed, API-driven systems and design AI-powered solutions that enhance our data platform used across CoStar brands. The role requires 3+ years of .NET development, cloud experience (AWS or Azure), RESTful services, and a strong grasp of data quality and observability.

Qualifications

• Bachelor’s Degree from an accredited university.
• 3+ years of .NET/C# development experience.
• Experience with cloud platforms (AWS or Azure) and RESTful services.
• Familiarity with large language models (LLMs) and AI workflows.
• Experience with monitoring, telemetry, observability, or automated diagnostics.

Responsibilities

• Build distributed, API-driven systems for tens of thousands of users.
• Design AI-powered software and integrate AI skills, agents, tools, and workflows.
• Produce robust, maintainable code using C#, .NET, SQL Server, AWS.
• Implement telemetry-driven solutions to identify anomalies and performance issues.
• Collaborate on code reviews and adhere to development standards.

Skills

C#/.NET

Distributed systems

RESTful services

Observability/Telemetry

LLMs familiarity

Data governance

Communication skills

SQL knowledge

Education

Bachelor’s Degree

Tools

Web API

AWS

Azure

SQL Server

Job description

CoStar Group, Inc. in Arlington, VA is seeking a Software Engineer I (C#/.NET) to contribute to the Platform Development team.

You will build distributed, API-driven systems and design AI-powered solutions that enhance our data platform used across CoStar brands. The role requires 3+ years of .NET development, cloud experience (AWS or Azure), RESTful services, and a strong grasp of data quality and observability.