Senior Software Engineer - LoopNet

costar; Irvine (CA); Hybrid; USD 150,000 - 190,000; Full time

Benefits offered by this job

Healthcare coverage (Medical/Vision/Ds

401(k) with matching

Tuition reimbursement

On-site fitness center

Job summary

CoStar Group is seeking a Senior Software Engineer for LoopNet in Irvine, CA. The role focuses on C#/.NET, AWS cloud development, and AI-assisted coding tools, contributing to scalable platforms across LoopNet and related brands.

You will participate in architecture decisions, mentor engineers, and drive delivery with modern AI-driven development practices. This is a hybrid role with four onsite days and one remote day.

Qualifications

• Bachelor's degree from an accredited university or college.
• 6+ years of production development experience with C#/.NET or .NET Core.
• Proven history of building and launching products and platforms.
• Experience delivering products meeting specifications and performance SLAs.
• Strong experience writing unit, performance, and automated end-to-end tests.
• Experience building APIs and backend systems with solid software design principles.
• Active participation in mentoring developers and building team consensus.

Responsibilities

• Contribute to building scalable, high-quality systems across multiple products and brands.
• Lead architecture decisions and mentor engineers across the team.
• Develop and maintain backend services with C#/.NET and AWS.”

Skills

C#/.NET

APIs

Backend systems

Unit tests

Mentoring

Architecture decisions

Education

Bachelor's degree

Tools

Docker

Kubernetes

AWS

Kafka

Datadog

Job description

Senior Software Engineer - LoopNet

Job Description

CoStar Group (NASDAQ:CSGP) is a leading global provider of commercial and residential real estate information, analytics, and online marketplaces. Included in the S&P 500 Index, CoStar Group is on a mission to digitize the world's real estate, empowering all people to discover properties, insights and connections that improve their businesses and lives.

We have been living and breathing the world of real estate information and online marketplaces for over 35 years, giving us the perspective to create truly unique and valuable offerings to our customers. We've continually refined, transformed and perfected our approach to our business, creating a language that has become standard in our industry, for our customers, and even our competitors. We continue that effort today and are always working to improve and drive innovation. This is how we deliver for our customers, our employees, and investors. By equipping the brightest minds with the best resources available, we provide an invaluable edge in real estate.

LoopNet, the most popular place to find a space, is the #1 global commercial real estate marketplace. With more than 12 million global unique monthly visitors, LoopNet provides brokers, buyers and sellers with what they need to meet and make deals. LoopNet has established itself as the most effective and far-reaching digital marketplace for commercial real estate owners and brokers. We are not done yet! We continue to focus on driving expansion by increasing market share in the US and abroad, continuously innovating and enhancing the product and growing a powerhouse global team to reach our goals. Learn more about LoopNet.

We are seeking a highly skilled Senior Software Engineer with deep expertise in C#/.NET, AWS cloud development, and hands‑on experience with AI coding tools such as Claude Code or GitHub Copilot. In this role, you will contribute to building scalable, high‑quality systems across multiple products and brands‑including LoopNet.com‑while leveraging modern AI‑driven development practices to accelerate delivery and improve code quality. You will also play a key role in architecture decisions and mentoring engineers across the team.

This position is located in Irvine, CA and offers 4 days a week onsite with 1 day work from home.

BASIC QUALIFICATIONS:

• Bachelor's degree from an accredited, not‑for‑profit university or college.
• A demonstrated track record of commitment with prior employers.
• 6+ years of production development experience with C# and .NET or .NET Core.
• Proven history of building and launching successful products and platforms.
• Experience delivering products that meet specifications and performance SLAs.
• Solid experience writing unit, performance, and automated end‑to‑end tests
• Strong experience building APIs and backend systems with a solid grasp of software design principles.
• Deep understanding of the business context for which you are building software.
• Active participation in mentoring developers and building team consensus.

PREFERRED QUALIFICATIONS:

• Working knowledge of Vue.js or React in TypeScript.
• Experience with relational database design (MS SQL or MySQL), including performance tuning.
• Hands‑on experience with AWS services including S3, SQS, DynamoDB, and ElastiCache, as well as Apache Kafka and Datadog.
• Experience with microservices, distributed systems, Docker, and Kubernetes.
• Familiarity with CI/CD pipelines, DevOps practices, and Infrastructure as Code tools.
• Application security knowledge and experience with Git‑based workflows.
• Hands‑on professional experience with AI coding tools such as Claude Code, GitHub Copilot, or equivalent.
• Experience with cloud data warehouse platforms (BigQuery, Databricks, or Snowflake) and proficiency in Python for data engineering or analytics workflows.

What's in it for You:

When you join CoStar Group, you'll experience a collaborative and innovative culture working alongside the best and brightest to empower our people and customers to succeed.

We offer you generous compensation and performance‑based incentives. CoStar Group also invests in your professional and academic growth with internal training, and tuition reimbursement.

Benefits:

• Comprehensive healthcare coverage: Medical / Vision / Dental / Prescription Drug
• Life, legal, and supplementary insurance
• Virtual and in person mental health counseling services for individuals and family
• Commuter and parking benefits
• 401(K) retirement plan with matching contributions
• Employee stock purchase plan
• Paid time off
• Tuition reimbursement
• On‑site fitness center and/or reimbursed fitness center membership costs (location dependent), with yoga studio, Pelotons, personal training, group exercise classes
• Access to CoStar Group's Employee Resource Groups
• Complimentary gourmet coffee, tea, hot chocolate, fresh fruit, and other healthy snacks

The final salary or hourly