Senior Software Engineer (Washington)

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

What you'll get in return

Zip is a place where you'll get out what you put in. The newness of our sector means we need to move at pace and embrace change, and our promise to you when you join the team is that you'll feel empowered and trusted to make big things happen quickly.

We want you to feel welcome and as though you have the support to be yourself, and care for yourself at work. Because it's important to us that you make the most of the opportunities you'll get to grow your skills and your career, and be surrounded by smart, friendly people and leaders that have your back.

We think these are just some of the best things about being a Zipster. We will also offer you :

Zip is committed to a straightforward and transparent pay structure. The actual base salary will be determined by various individualized factors, including job-related knowledge, skills, experience, location, internal equity, as well as other objective business considerations. The annual base Pay Range for this position is $140,000- $160,000 USD This range reflects our US national compensation (USN). Subject to those same considerations, the total compensation package for this position may also include other elements, including a bonus and / or equity awards, in addition to a full range of medical, financial, and / or other benefits.

If hired, employees will be in an 'at-will position' and the Company reserves the right to modify base salary (as well as any other discretionary payment or compensation or benefit program) at any time, including for reasons related to individual performance, Company or individual department / team performance, and market factors.

Be a part of a team that reflects the diversity of our customers

We pride ourselves on being a workplace that provides equal opportunities to people of all ages, cultural backgrounds, sexual orientations, gender identities, abilities, veteran status, and everything else that makes you unique. Equally, we're committed to ensuring our recruitment processes are accessible and inclusive. Please let us know If there are any adjustments that need to be made to ensure you have a fair and equitable experience.

And finallyget to know us

Zip Co Limited (ASX : ZIP) is a digital financial services company, offering innovative, people-centered products. Operating in two core markets - Australia and New Zealand (ANZ) and the US, Zip offers access to point-of-sale credit and digital payment services, connecting millions of customers with its global network of tens of thousands of merchants. We're proud to be a values-led business and our values - Customer First, Own it, Stronger Together and Change the Game - guide us in everything we do.