Senior Software Engineer

• Senior Software Engineer with deep .NET/C# expertise who designs scalable, resilient, and secure APIs and distributed systems to power merchant checkout and B2B payment flows in a high-traffic, cloud-native platform.
• Excels in domain-driven design and cross-functional collaboration, enabling robust integrations, financial reconciliation, and feature configuration while mentoring teams and championing architectural excellence and observability.
• Remote-first opportunity for US-based employees with the option to work in-person out of our Manhattan office

Start your adventure with Zip 

Join Zip’s Engineering function and put your name to solving fascinating challenges at scale in an agile, test-driven development environment. If you value good domain-driven design and enjoy delivering quality work at pace, you’ll be a great fit with the squads responsible for building cloud-native software applications that serve millions of customers and process billions of dollars in payments.

We’re hiring a Senior Software Engineer to drive technical excellence across our Merchant & Checkout team, helping design and scale core systems that power how merchants integrate with Zip.

This is a high-impact, senior role in a distributed platform environment.  You’ll be responsible for designing and building resilient APIs and services that support key B2B payment and order flows - enabling merchants to initiate checkouts, get paid, and manage transactions across their entire lifecycle.

You’ll work at the intersection of commerce, finance, and integration, designing solutions that give merchants clear visibility into the orders they send Zip, and ensure all parties remain financially reconciled.

Interesting problems you’ll get to solve

• Design and build scalable APIs for merchant integrations (checkout initiation, pre-qualifications, order confirmation, capture and refunds)
• Support customer checkout flows, including complex scenarios like pre-orders, backorders, and add-ons (insurance, warranty)
• Support flexible merchant configuration - enabling internal teams (e.g. account managers, integration managers) to control which features and flows are enabled per merchant
• Own architectural decisions that support an event-driven, domain-oriented backend using .NET, C#, and Azure Cloud Services
• Implement distributed systems using DDD and CQRS
• Integrate with third-party accounting systems to support financial operations and reconciliation
• Collaborate with security to implement robust authentication patterns, tokenization strategies, and secure key management practices (e.g. key rotation) 
• Ensure our systems align with regulatory requirements, including TILA
• Lead design and code reviews to elevate architecture and execution across the team
• Collaborate with Product Managers and Engineering Managers to define roadmap trade-offs, sequence delivery, and de-risk technical unknowns
• Proactively improve observability, reliability, and incident response for production systems
• Mentor engineers across the team through pairing, feedback, and knowledge sharing
• Champion best practices for testing, monitoring, and alerting across our service landscape

What you’ll bring to the team 

• 10+ years of hands-on software engineering experience, including senior-level architecture and delivery ownership
• Deep expertise with .NET / C#, Azure Cloud Services, and building distributed systems in a modern backend environment
• Demonstrated ability to design systems using Domain-Driven Design (DDD), CQRS, and event-driven architectures
• Experience building B2B platforms or integrations, where external partners rely on stable, well-defined contracts - you understand the importance of backward compatibility, clear communication, and long-term reliability with partner-facing integrations
• Strong understanding of authentication and security fundamentals, including key management and securing B2B integrations
• Hands-on experience with financial or transactional systems - you understand concepts like order lifecycle, refunds, invoicing, and reconciliation, and have worked on systems where correctness and traceability are critical
• Familiarity with accounting platforms such as NetSuite, and an understanding of how businesses reconcile external payment data with internal finance systems
• Proven experience leveraging AI-based tooling (e.g., GitHub Copilot, CodeWhisperer, ChatGPT, or similar) to enhance code quality, productivity, and problem-solving workflows
• An architecture mindset, with the ability to design and evolve APIs and services that support flexibility, scalability, and clear separation of concerns
• Comfort work