Senior Software Engineer

CoStar; San Diego (CA); On-site; USD 124,000 - 187,000; Full time

Benefits offered by this job

Healthcare coverage

401(k) match

Employee stock purchase plan

Tuition reimbursement

On-site fitness center

Mental health services

Job summary

CoStar Group is seeking a Senior Software Engineer in San Diego, CA, to design, build, and operate cloud-native applications using C#/.NET and AWS. The role includes leveraging Claude for AI-assisted development and mentoring junior engineers.

You'll contribute to scalable system design, API development, and code reviews while working across product and architecture teams. The position follows a 4-on/1-remote work schedule with competitive compensation.

Qualifications

• Bachelor’s degree in a relevant field from an accredited institution.
• Strong experience with C#/.NET/.NET Core and APIs.
• Hands-on AWS experience with EC2, ECS/EKS, Lambda, S3, RDS, DynamoDB, CloudWatch.

Responsibilities

• Design, build, and maintain production applications using C# and .NET.
• Leverage Claude for code generation, refactoring, debugging, and analysis.
• Build and operate cloud-based solutions on AWS.
• Collaborate with product, architecture, and engineering teams.
• Participate in system design, code reviews, and technical decision-making.
• Improve performance, scalability, and reliability of applications.
• Mentor engineers and contribute to engineering best practices.

Skills

C#/.NET

AWS

Claude AI

API design

Backend services

CI/CD

Microservices

Education

Bachelor's degree

Tools

Databricks

Terraform

CloudFormation

CDK

Job description

Overview

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.

Role Description

We’re seeking a Senior Software Engineer with strong C#/.NET experience, hands‑on use of Claude for AI‑assisted development, and proven experience building and operating systems on AWS. This role focuses on developing scalable, cloud‑native solutions while leveraging modern AI tools to accelerate development and improve code quality. The position is located in San Diego, CA and has a work schedule of 4 days onsite and 1 day work from home.

Responsibilities

• Design, build, and maintain production applications using C# and .NET
• Leverage Claude for code generation, refactoring, debugging, and analysis
• Build and operate cloud‑based solutions on AWS
• Collaborate with product, architecture, and engineering teams
• Participate in system design, code reviews, and technical decision‑making
• Improve application performance, scalability, and reliability
• Mentor engineers and contribute to engineering best practices

Basic Qualifications

• Bachelor’s degree required from an accredited, not‑for‑profit, in‑person college/university
• A track record of commitment to prior employers
• Strong experience with C# and .NET / .NET Core
• Hands‑on AWS experience (EC2, ECS/EKS, Lambda, S3, RDS, DynamoDB, CloudWatch)
• Experience building APIs and backend services
• Solid understanding of software design principles

  Preferred Qualifications

  • Practical experience using Claude for coding or code review
  • Experience with Databricks
  • Microservices or distributed systems experience
  • CI/CD pipelines and DevOps practices
  • Infrastructure‑as‑Code (Terraform, CloudFormation, CDK)
  • Experience with additional AI coding tools

  Benefits

  Generous compensation and performance‑based incentives. CoStar Group also invests in your professional and academic growth with internal training and tuition reimbursement.

  • 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, Peloton, 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

  Salary

  This position offers a base salary range from $124,000 to $187,000 a year, determined by relevant skills and experience, and a generous benefits plan.

  Additional Information

  We welcome all qualified candidates who are currently eligible to work full‑time in the United States to apply. However, please note that CoStar Group is not able to provide visa sponsorship for this position.

  Legal Notice

  CoStar Group is an Equal Employment Opportunity Employer; we maintain a drug‑free workplace and perform pre‑employment substance abuse testing.