Senior Software Engineer

Who We Are Finance leaders choose Billtrust to get paid faster, control costs, and maximize customer satisfaction. As the leader in B2B accounts receivable workflow and payment software, we provide the world’s leading brands with AI-powered solutions across the full AR lifecycle—from invoice presentment and payment processing to cash application and collections. With over 2,600 global customers, more than $1 trillion in invoice dollars processed, and a proprietary network of 13 million buyers, Billtrust delivers business value through deep industry expertise and a culture relentlessly focused on meaningful customer outcomes. We’re an AI-first company, not just in what we build for our customers, but in how we work. Across every function, our teams use AI tools daily to work faster, make better decisions, and deliver higher-quality outcomes. We hire exceptional people, give them cutting-edge AI capabilities, and measure success by the impact they create. If you want to do the best work of your career at the frontier of AI and fintech, Billtrust is the place to do it. Our Values Customers We relentlessly increase value for customer and do the right thing for them. Action We make ‘thoughtfully fast’ decisions, act quickly, cut through red tape, deliver progress not perfection, take ownership and accountability. Team Spirit We put the team ahead of ourselves, foster trust and respect, collaborate with passion, despise toxic politics, value our differences, and celebrate together. Innovation We challenge the status quo, experiment thoughtfully, and are novel and brilliant in what we create. Excellence We love to win, but we hate losing even more. We aspire to be the best and take pride in our work. When we fall short, we own it and come back stronger. About the Role The Sr. Software Engineer is a critical role responsible for designing solutions and delivering complex features across our product platforms. You will leverage AI tools and co-worker agents such as Claude Code to specify, implement, validate, deploy, and support features end-to-end, focusing your expertise on architectural judgment, code quality, and mentorship. As a senior member of a domain-aligned cohort, this position contributes deep expertise to the cohort’s product domain and interfaces with the Engineering Manager, Product Manager, and fellow cohort members to deliver scalable SaaS products with high velocity. You’ll drive the evolution of AI-assisted development practices, mentor engineers within the cohort on effective AI tool usage, and share knowledge across cohorts. What You’ll Do Specification & Technical Collaboration • Own end-to-end specification quality for complex features, ensuring specs are comprehensive, unambiguous, and address all edge cases and non-functional requirements • Collaborate with the Product Manager to translate complex product requirements into detailed technical specifications • Lead technical decisions and contribute to domain expertise within your cohort • Other duties as assigned. AI-Assisted Implementation & Quality • Lead AI-assisted implementation for complex features, using AI coding tools such as Claude Code to generate implementations from specifications • Review AI-generated code and peer contributions for correctness, security, performance, and architectural alignment • Validate AI-generated tests and ensure comprehensive test coverage for complex scenarios • Drive improvements to AI-assisted development practices within your cohort, including spec templates, prompt patterns, and validation workflows Software Design, Delivery & Mentorship • Design performant software with a DevOps mindset that will scale as our volumes increase, and design and implement REST APIs following established patterns • Support and maintain both UI and backend services within your cohort’s domain • Mentor engineers within your cohort on effective AI tool usage, spec writing techniques, and code review practices, and share knowledge and experien…