Staff Software Engineer, Invoicing and Billing

About Gusto At Gusto, we're on a mission to grow the small business economy. We handle the hard stuff — payroll, health insurance, 401(k)s, and HR — so owners can focus on their craft and their customers. With teams in Denver, San Francisco, and New York, we support more than 500,000 small businesses nationwide and are building a workplace that reflects the people we serve. All full-time employees receive competitive base pay, benefits, and equity (RSUs) — because everyone who helps build Gusto should share in its success. Offer amounts are determined by role, level, and location. Learn more about our Total Rewards philosophy . AI is a fundamental part of how work gets done at Gusto. We expect all team members to actively engage with AI tools relevant to their role and grow their fluency as the technology evolves. AI experience requirements vary by role and will be assessed during the interview process. We're looking for seasoned backend software engineers to join the teams behind Gusto's Invoicing and Billing platform — the billing platform that generates accurate invoices for our customers and integrates with our revenue and accounting systems. As a Staff Software Engineer, you'll operate across the full lifecycle of Gusto’s commerce systems: shaping architecture early in the design process, improving and maintaining a high throughput transactional billing platform, building self-service internal features and APIs, and owning their performance long after launch. That means engineering the core commerce engine, enabling product teams to launch new products and Gusto to monetize its offering. Support new billing models for Gusto like multi-entity, multi-currency anniversary billing. If you're drawn to work that combines technical craft with real-world impact — helping power the livelihoods of millions using Gusto products — join us! Here’s what you’ll do day-to-day: Design, build, and test Gusto core billing platform – usage jobs, subscriptions, orders, invoice generation, payments, reporting, accounting integrations. Mentor other engineers to help solve some of the hardest technical problems out there in very complex domains and at a large scale. Help scale one of the largest Ruby/Rails and Javascript/React applications in the world. Collaborate with our Product Engineering, Product Management, Data, and Design teams to understand customer pain points, come up with solutions, and then prototype, iterate, and launch daily. Build products that our customers genuinely love. Here’s what we’re looking for: Successful applicants typically have 8+ years of software development experience. Passion for creating scalable, efficient platforms for users. Experience leveraging AI tools or systems to accelerate development, improve testing, and deliver new platform capabilities. Curiosity and experimentation with emerging AI frameworks , applying and sharing best practices to evaluate and scale AI use safely across teams Experience in building large high throughput distributed systems. Experience in the Commerce domain: invoicing, commerce, payment processing space revenue recognition. Experience owning multi-quarter projects that solve complex engineering problems and make measurable user impact at scale. Experience with large scale refactors, performance and reliability issues, and a strong sense of ownership over all aspects of your platform area. Ability to mentor engineers to maximize their performance and impact. Experience in, or interest working in, Ruby on Rails. Ability to effectively communicate across engineering teams and with business stakeholders. Please note that travel to Gusto's office for onboarding is required for this position. If you have any questions regarding this requirement, please share with your recruiter. Our cash compensation amount for this role is targeted at $163,000–$204,000 in Denver & most remote locations, and $197,000–$247,000 for Sa