Senior C#/.NET Engineer — Cloud, Claude AI, Hybrid

CoStar Group, Inc.; San Diego (CA); Hybrid; USD 150,000 - 190,000; Full time

Benefits offered by this job

Healthcare coverage

401K with matching

Employee stock purchase plan

Tuition reimbursement

Paid time off

Job summary

CoStar Group, based in San Diego, seeks a Senior Software Engineer to design, build, and scale cloud-native applications using C#/.NET. The role emphasizes AI-assisted development with Claude and AWS-based services, while maintaining high performance and reliability in production systems.

The position is 4 days onsite with 1 day remote, offering collaboration with product and architecture teams and mentorship to engineers.

Qualifications

• Bachelor’s degree (accredited college/university)
• 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
• Experience with Git-based workflows

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

Skills

C#/.NET

Claude AI

AWS

APIs and backend services

Git-based workflows

CI/CD

Terraform/DevOps

Databricks

Distributed systems

Education

Bachelor’s degree

Tools

EC2

ECS/EKS

Lambda

S3

RDS

DynamoDB

CloudWatch

Terraform

CloudFormation

CDK

Databricks

Job description

CoStar Group, based in San Diego, seeks a Senior Software Engineer to design, build, and scale cloud-native applications using C#/.NET. The role emphasizes AI-assisted development with Claude and AWS-based services, while maintaining high performance and reliability in production systems.

The position is 4 days onsite with 1 day remote, offering collaboration with product and architecture teams and mentorship to engineers.