Senior Backend Engineer - Financial Infrastructure (Gusto Retirement)

About the Role:

You’ll be a key engineer focused on building and owning the systems that move money and assets through Gusto Retirement. This is a very hands-on role: owning backend services and APIs end-to-end, shipping production code, and working through real financial edge cases. You’ll partner closely with product, compliance, and operations to turn complex financial requirements into reliable software. If you like working on core systems where correctness matters and enjoy getting things shipped, you’ll be a great fit.

About the Team:

The Financial Infrastructure team owns the core money and asset flow systems for Gusto Retirement. We’re a senior team that works on payments, settlements, tax and compliance integrations, and much more. The work is complex and often cross-functional, so we stay focused, collaborate closely, and keep tight ownership of what we build. We work closely with product and partner teams, but we’re responsible for execution and reliability end-to-end.

Here’s what you’ll do day-to-day:

• Design, build, and ship services and APIs for money movement and financial integrations
• Work on payments, settlements, reconciliation, and corrections involving real customer funds
• Build and support critical workflows like payroll integration, KYB/KYC, 401k loans, billing and invoicing, and IRA
• Partner with product, compliance, and operations to scope work and deliver production-ready solutions
• Debug production issues and improve reliability, observability, and operational tooling
• Collaborate with other engineering teams to integrate with shared systems and platforms
• Mentor other engineers to help solve some of the hardest technical problems out there in very complex domains and at a large scale
• Write clear, reliable, well-tested code that ships quickly and scales well
• Build a product that our customers genuinely love

Here’s what we’re looking for:

• 8+ years of software engineering experience building and shipping production products or platforms
• Strong experience with services, APIs, and data-heavy workflows.
• Experience working on financial systems, payments, or other high-correctness domains (or the ability to ramp quickly).
• Comfortable owning systems end-to-end, including production support and operational work.
• Experience working closely with PMs and cross-functional partners to deliver scoped work.
• Pragmatic, execution-focused approach to engineering.
• Clear communicator and collaborative teammate.
• Ability to mentor engineers to maximize their performance and impact
• Experience with Ruby on Rails (or a comparable backend framework).

Bonus Points:

• Experience leveraging AI tools or systems to accelerate development, improve testing, and deliver new product capabilities.
• Curiosity and experimentation with emerging AI frameworks, applying and sharing best practices to evaluate and scale AI use safely across teams.