Senior Software Engineer - .NET

About us At Auctane, we are united by a passion to help businesses deliver — whatever their size, wherever they are, and however they operate. We make it possible for businesses to meet the ever-changing requirements of their industry and customer expectations. Auctane products enable hundreds of thousands of businesses to annually mail and ship billions of items — over $200 billion worth — to recipients around the globe. The Auctane family of mailing and shipping software products includes ShipStation, Stamps.com, ShipStation API, Metapack, GlobalPost, and Packlink. Our partners include Amazon, UPS, USPS, eBay, BigCommerce, Shopify, WooCommerce, and Walmart. Our values Win as One. Delight Customers. Deliver Great Outcomes. About the role We're seeking an experienced Senior Software Engineer - .NET to join our engineering team. In this role, you'll architect and build scalable backend systems that power our applications, working across our modern tech stack to deliver robust, high-performance solutions. This position is focused on the ShipStation API brand. This position is hybrid (3 days per week in office - Tuesday through Thursday) and is located in Austin, TX . What will you be doing? You'll design and implement backend services and APIs that serve millions of requests, working closely with frontend teams to create seamless user experiences. Your work will involve building new features, optimizing existing systems, and making key architectural decisions that shape our platform's future. You'll mentor other engineers, participate in code reviews, and help establish best practices across the team. System Architecture & Design : Architect, build, and maintain scalable, robust backend services and microservices using C# and .NET. API Development : Create and consume secure REST APIs for seamless communication between backend services and front-end/mobile applications. Database Management : Design, query, and optimize relational databases (both SQL and NoSQL). Code Quality & Best Practices : Conduct rigorous code reviews, enforce engineering standards, and write clean, maintainable, production-ready code. Mentorship : Provide technical guidance, support, and mentorship to mid-level and junior developers. DevOps & Cloud : Collaborate with the infrastructure team to configure CI/CD pipelines, deploy applications to the cloud (AWS), and maintain different environments. Testing : Develop and maintain unit tests and integration tests to ensure application reliability. What are we looking for? Required Technologies: .NET - Strong proficiency in .NET, including ASP.NET Core, Entity Framework Core, and building RESTful APIs. Experience with C# design patterns and async programming AWS - Hands-on experience deploying and managing services on AWS, including EC2, Lambda, RDS, S3, CloudFront, SQS and API Gateway. Familiarity with infrastructure as code (Terraform, CloudFormation or CDK) React - Some experience…