Sr. Core Backend Engineer

We Are Cobalt Streamworks When shoppers hit "buy," a great customer experience doesn’t end, it’s just getting started. For too long, everything after checkout has been the weakest link in ecommerce: confusing tracking, lost or damaged packages, clunky returns, and missed opportunities to turn first-time buyers into lifelong fans. That's why we built Cobalt Streamworks. Our mission is simple: we create shopper confidence that fuels brand growth. Cobalt Streamworks is the leading post-purchase platform for modern ecommerce, trusted by over 13,000 brands and protecting more than $20 billion in gross merchandise value to date. From package protection and industry-leading order tracking to returns and exchanges, cash back loyalty, and engaging product recommendations, Cobalt Streamworks brings every moment after checkout into one powerful platform, empowering shoppers with visibility and peace of mind while giving merchants loyalty that lasts well beyond the first sale. Since launching in 2018, Cobalt Streamworks has raised over $250 million from leading investors including Craft Ventures, Hedosophia, and Hanaco Ventures, and has grown into a complete post-purchase ecosystem loved by millions of shoppers and the brands they buy from. Throughout that growth, we've stayed committed to building innovative products that empower our customers and to fostering a people-first, values-driven culture that makes Cobalt Streamworks a place where great work and great people thrive. We're looking for talented people across the ecommerce space to join us on the next chapter of this adventure. Don't just take our word for it, Discover what life at Cobalt Streamworks has to offer. The team The Core Backend Engineering team builds the foundational systems that power Cobalt Streamworks’s post-purchase experience and help connect the world’s commerce through innovative, scalable products. Our team owns the highly available, business-critical services behind Package Protection, Returns Protection, claims, order management, shipment tracking, merchant integrations, and more. Core Engineers solve complex distributed systems challenges at scale, building reliable platforms, APIs, and services that process millions of events and support merchants, partners, consumers, and internal teams every day. As a member of the Core team, you’ll help shape the architecture behind Cobalt Streamworks’s continued growth while collaborating with a talented engineering organization passionate about creating seamless commerce experiences for millions of consumers around the world. The opportunity The Core Backend team at Cobalt Streamworks is looking for a Senior Backend Engineer to help design, build, and scale the services that power our end-to-end post-purchase experience. In this role, you’ll solve complex backend challenges across our Orders platform, Tracking services, merchant APIs, third-party integrations, and other foundational systems that support millions of shipments. You’ll partner closely with Product Managers, Engineering teams, and external partners to deliver reliable, scalable solutions that create seamless experiences for merchants and consumers. We’re looking for someone who thrives in complex distributed systems, takes ownership from design through production, and is passionate about building technology that has meaningful business impact. You’ll influence technical decisions, mentor other engineers, establish best practices, and help shape the future of Cobalt Streamworks’s core platform. What you’ll do Design, build, test, deploy, and maintain highly scalable backend services using Go. Own critical services supporting Package Protection, Returns Protection, Claims, Orders, Tracking, and Email Parsing. Design and evolve distributed systems and event-driven architectures that process high volumes of transactions reliably. Build and maintain REST and GraphQL APIs used by internal products, merchants, and external partners. Develop and improve integrations with merchant platforms, carriers, and third-party APIs. Optimize system performance, reliability, scalability, and observability across production services. Collaborate closely with Product Managers, Engineers, and cross-functional stakeholders to deliver impactful solutions. Mentor engineers through technical leadership, design reviews, and knowledge sharing. Participate in architectural decisions and continuously improve engineering standards and operational excellence. What we’re looking for 7+ years of professional software engineering experience designing, building, and scaling backend systems. Experience designing, deploying, and supporting distributed systems in production environments. Proficiency with Go, or experience with another modern backend language and excitement to build expertise in Go. Experience building and maintaining cloud-based services, preferably within AWS environments. Experience working with relational databases, distributed databases, and NoSQL technologies (such as CockroachDB, DynamoDB, or similar platforms). Experience designing and building scalable APIs, including REST, GraphQL, or simi