Senior Software Engineer - C#/.NET & AWS (Hybrid)

CoStar Group, Inc.; California (MO); Hybrid; USD 118,000 - 154,000; Full time

Benefits offered by this job

Health, vision, dental, and Rx

401(k) matching

Employee stock purchase plan

Paid time off

Tuition reimbursement

On-site fitness center or subsidized

Commuter benefits

On-site amenities

Job summary

CoStar Group in Irvine, CA is seeking a Senior Software Engineer with deep expertise in C#/.NET and AWS to build scalable systems across LoopNet and other products. You will influence architecture, mentor teammates, and apply AI‑driven development practices in a hybrid role (4 days onsite, 1 day remote).

You will design, develop, and deploy high‑quality back‑end services, write robust tests, and ensure performance SLAs while collaborating across teams and driving engineering excellence.

Qualifications

• Bachelor’s degree from an accredited, not-for-profit institution.
• 7+ years of production development experience with C# and .NET (or .NET Core).
• Demonstrated history of building and launching successful products and platforms.
• Experience delivering products that meet specifications and performance SLAs.
• Solid experience building APIs and back‑end systems with strong software design principles.
• Deep understanding of business context for which software is built.
• Active participation in mentoring developers and building team consensus.

Responsibilities

• Design, develop, and deploy high‑quality, scalable systems across multiple LoopNet products.
• Apply modern AI coding tools to accelerate delivery and improve code quality.
• Make key architecture decisions and enforce best practices across the engineering team.
• Mentor junior developers and foster technical consensus.
• Write robust unit, performance, and end‑to‑end tests, and maintain high code coverage.

Skills

C#/.NET

AWS

API design

Mentoring

Unit testing

Docker

Kubernetes

CI/CD

AI coding tools

Education

Bachelor’s degree

Tools

Vue.js

React with TypeScript

MS SQL

MySQL

Kafka

Datadog

Docker

Kubernetes

CI/CD

Git-based workflows

Job description

CoStar Group in Irvine, CA is seeking a Senior Software Engineer with deep expertise in C#/.NET and AWS to build scalable systems across LoopNet and other products. You will influence architecture, mentor teammates, and apply AI‑driven development practices in a hybrid role (4 days onsite, 1 day remote).

You will design, develop, and deploy high‑quality back‑end services, write robust tests, and ensure performance SLAs while collaborating across teams and driving engineering excellence.