Senior Software Engineer, Full Stack; Zero to One Labs

Affirm is reinventing credit to make it more honest and friendly, giving consumers the flexibility to buy now and pay later without any hidden fees or compounding interest.

Zero To One (ZT1) is affirm’s 0 -> 1 innovation lab, focused on turning bold ideas into validated new businesses. Operating outside the standard Product and Engineering structure, ZT1 is built for speed, autonomy, and decisive execution. We run fast, hypothesis-driven experiments with a clear goal: prototype quickly, generate real signals, and drive explicit ‘kill or scale’ decisions on high-impact opportunities, with AI as a core enabler across the stack.

As an engineer on ZT1, you will work in a small, highly empowered, AI-native team alongside product managers and cross‑functional partners, with direct exposure to senior leadership. You will not just build systems, you will help shape experiments, define technical approaches, and influence product direction. Work happens in rapid sprint cycles, where ideas quickly move from concept to AI‑powered prototypes and real‑world testing.

Engineers on this team are expected to be comfortable leveraging AI‑first tools and approaches, including AI‑assisted development, agentic workflows, automation, and rapid prototyping. You should have an eye for product and design, and be able to quickly translate ideas into functional, AI‑enabled prototypes that can be tested with users or stakeholders.

This role is ideal for engineers who thrive in ambiguity, move quickly, and take ownership end to end in an AI‑centric environment. You will balance speed with sound engineering judgment, contributing to both early prototypes and scalable AI‑driven solutions when ideas prove viable. If you enjoy building from scratch and seeing your work directly impact company strategy, ZT1 offers a uniquely high‑leverage environment.

• You will be responsible for owning and delivering quarterly goals for your team, leading engineers on your team through ambiguity to solve open-ended problems, and ensuring that everyone is supported throughout delivery.
• You will support your peers and stakeholders in the product development lifecycle by collaborating with product management, design & analytics by participating in ideation, articulating technical constraints, and partnering on decisions that properly consider risks and trade-offs.
• You will proactively identify project, process, technology or business issues, advocate for them, and lead in solving them.
• You will support the operations and availability of your team’s artifacts by creating and monitoring metrics, escalating when needed, and supporting “keep the lights on” & on‑call efforts.
• You will foster a culture of quality and ownership on your team by setting or improving code review and design standards for your team, and advocating for them beyond your team through your writing and tech talks.
• You will help develop talent on your team by providing feedback and guidance, and leading by example.

• You have a total of 4+ years of experience as a software engineer.
• You are experienced in designing, developing and launching backend systems at scale technologies like Python, Kotlin, AWS, MySQL, and Kubernetes.
• You have experience shipping web apps using declarative UI frameworks like React or Vue.
• You have experience leveraging AI tools, agentic coding workflows, and automation to accelerate development, prototyping, and problem solving.
• You have experience defining a technical plan for the delivery of a significant feature or system component with an elegant, simple and extensible design. You write high quality code that is easily understood and used by others.
• You are proficient at making significant changes in a large code base, and have developed a suite of tools and practices that enable you and your team to do so safely.
• Your experience demonstrates that you take ownership of your growth, proactively seeking feedback from your team, your manager, and your stakeholders.
• You have strong verbal and written communication skills that support effective collaboration with our global engineering team.
• This position requires either equivalent practical…