Software Engineer (C#/.NET)
CoStar · Arlington, VA
$108,000–$154,000from the description
Jul 9, 2026
Arlington, VA
Jul 21, 2026
What this job asks for AI summary
A mid-level backend engineering role focused on building and maintaining a large-scale, distributed data platform that underpins several major real estate brands. Day-to-day work spans designing API-driven services in C# and .NET, integrating AI agents and LLM-based tooling into internal and customer-facing systems, and implementing telemetry and observability solutions. Suits engineers with solid distributed-systems experience who are comfortable applying AI technologies within a cloud environment.
Mid level · 3+ years · Washington-Arlington-Alexandria, DC-VA-MD-WV · Bachelor's required · Full-time
“or” means any one of them counts — you don't need all of them.
Posted 2 times — it's one opening, so apply once.
We read this from the posting text with AI. Skim the description below before ruling yourself out.
How this req sits in the market our data
Rare in this occupation — lead with these, and say what you built with them.
What the occupation pays Median $158,337 (middle half $126,441–$180,105). This posting is about at that midpoint.
Estimated from BLS employment for this occupation and area, per-skill prevalence across our listing corpus, and published wage benchmarks — as of Jul 28, 2026. It is a model, not a headcount.
Why we read it this way (6)
The role is titled simply 'Software Engineer' with no level modifier; advertised seniority is Unspecified. The 3+ year .NET requirement and scope (team contributor on a platform) support a Mid-level classification.
The degree requirement is unusually specific: the JD explicitly gates on a degree from an 'accredited, not-for-profit, in-person university or college' — online-only degrees are excluded by the posting's own language.
LLMs/prompt engineering/agent-based architectures appear under Basic Qualifications with 'familiarity' language. This is a softer gate than the core .NET requirement, but it is in the required section, so it is treated as a hard requirement. Hiring managers should note the bar is 'familiarity,' not deep expertise.
Monitoring/telemetry/observability experience also appears under Basic Qualifications but names no specific tool (e.g. Datadog, New Relic, CloudWatch); no named-tool skill was emitted to avoid inventing a requirement.
SQL and database development knowledge, AWS PaaS services (Lambda, DynamoDB, SQS), and AI agent/workflow automation experience are listed under Preferred Qualifications.
The role is hybrid (in-office Mon–Thu, WFH Friday) at the Arlington, VA office — not fully remote.
Read the full posting
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