Senior Software Engineer, Fullstack (Card Acquisition)

At Affirm, we exist for the moments that matter—giving people a clear, predictable way to pay over time, with no hidden fees, no surprises, and no tradeoffs on what matters most.

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.

Affirm is seeking a Senior Full Stack Software Engineer to join the Acquisition & Onboarding team within the Consumer org. This is a high-impact leadership role for an engineer who can set technical direction, drive architectural decisions, and elevate the quality and velocity of full stack development across mobile, web, and backend systems. The team plays a critical role in shaping the first experience customers have with Affirm—building trust, clarity, and value from the very first interaction. As a Senior Engineer, you will be responsible for defining long-term technical strategy, mentoring senior engineers, and acting as a force multiplier through your technical depth, operational excellence, and ability to navigate ambiguity. You'll work at the intersection of product, design, and engineering to build polished, performant, and accessible user experiences that directly impact conversion, retention, and business growth.

What You'll Do

You will be responsible for owning and delivering quarterly goals for your team, leading engineers through ambiguity to solve open-ended problems, and ensuring that everyone is supported throughout delivery.

Support peers and stakeholders in the product development lifecycle by collaborating with product management, design, and analytics, participating in ideation, articulating technical constraints, and partnering on decisions that properly consider risks and trade-offs.

Take ownership of your team’s operations and availability by ensuring you have the right monitoring, triage rotations, playbooks, policies, testing and alerting in place to support “keep the lights on” & on-call efforts.

Proactively identify project, process, technology, or business issues, advocate for them, and lead in solving them.

Support the operations and availability of your team’s artifacts by creating and monitoring metrics, escalating when needed, and supporting “keep the lights on” and on-call efforts.

Foster a culture of quality and ownership by setting or improving code review and design standards for your team, and advocating for them beyond your team through writing and tech talks.

Help develop talent on your team by providing feedback and guidance, and leading by example.

What We Look For

You have experience leading significant mobile initiatives (React Native or native), including defining architecture, coordinating cross-functional launches, and maintaining high reliability in production environments.

Working across the React Native and native boundaries (Swift/Kotlin), debugging platform-specific issues and improving developer tooling, CI/CD, and release processes for mobile apps.

Implementing experimentation, feature flagging, and analytics instrumentation in mobile applications, ensuring safe rollouts and measurable impact.

Shipping web apps using declarative UI frameworks like React or Vue.

Proficient in working with JavaScript/TypeScript.

4+ years of experience as a software engineer.

Designing, developing, and launching backend systems at scale using technologies like Python, Kotlin, AWS, MySQL, and Kubernetes.

Defining a technical plan for the delivery of a significant feature or system component with an elegant, simple, and extensible design, and you write high-quality code that is easily understood and used by others.

Proficient at making significant changes in a large codebase and have developed a suite of tools and practices that enable you and your team to do so safely.

Demonstrates that you take ownership of your growth, proactively seeking feedback from your team, your manager, and your stakeholders.

Strong verbal and written communication skills that support effective collaboration with a global engineering team.

This position requires either equivalent practical experience or a Bachelor’s degree in a related field.