Junior .NET Engineer: AI-Powered APIs & Cloud

CoStar Group

Arlington (VA)

On-site

USD 108,000 - 154,000

Full time

14 days+

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Benefits offered by this job

Healthcare coverage

401(k) retirement plan

Employee stock purchase plan

Paid time off

Job summary

CoStar Group in Arlington, VA is seeking a Software Engineer I to develop distributed API-driven services using C# and .NET. You will design, implement, and maintain AI-enabled features and data integrations across our real estate platforms.

Work with AWS, SQL Server, and modern tooling to deliver reliable software; participate in code reviews, telemetry, and ongoing performance tuning while growing your skills in a collaborative, fast-paced environment.

Qualifications

Bachelor’s Degree from an accredited, in-person university or college.
3+ years of deep .NET development (C#) including cross-platform communication technologies such as Web API.
Working knowledge of cloud platforms (AWS or Azure).
Experience with RESTful web services.
Experience in 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 and data governance concepts.

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 into internal systems and customer apps.
Produce robust, maintainable code using C#, .NET Framework, SQL Server, AWS, Claude Code.
Leverage AI models to improve monitoring, observability, diagnostics, and reliability.