Senior Software Engineer, Identity Team (Remote UK)

About Affirm

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.

Role Overview

The Identity team at Affirm is mission-critical to the customer checkout experience. When a customer chooses Affirm, one of the first steps is an identity check, and our ability to make the right decision directly impacts conversion, revenue, fraud exposure, and regulatory compliance. Our team owns KYC, user lifecycle management, and identity decisioning across multiple regulatory environments for markets outside North America. This role involves shaping how Affirm adapts its core Identity platform to new market dynamics, customer expectations, and compliance requirements.

Team & Responsibilities

We are a team of six engineers based across Spain and Poland. We are looking for a Senior Software Engineer who can turn ambiguous business and customer problems into reliable, well-designed technical solutions.

In this role, you will:

• Help shape our quarterly technical direction, translate team goals into concrete projects, and identify cross-cutting risks, tradeoffs, and opportunities.
• Design across system boundaries, drive collaboration with partner teams, and advocate for technical investments that improve long-term execution.
• Take ownership beyond shipping code: raise code quality and review standards, make performance, availability, and scale tradeoffs explicit, and improve the operational health of the systems you own.
• Reduce toil, create useful playbooks, mentor engineers, support new hires and interns, and contribute to high-signal hiring.
• Leave things better than they found them, communicate clearly across audiences, use customer feedback to influence technical plans, and help the team continuously improve.

Core Responsibilities

This is a deeply technical, hands-on coding role where feature velocity and operational excellence go hand-in-hand. You’ll spend most of your week in the codebase:

• Leveraging AI tools to write robust Kotlin and Python.
• Shipping impactful features.
• Investigating complex production issues.
• Keeping our systems rock-solid and reliable.

This is a high-visibility, high-impact role for someone who wants to work on foundational systems that directly enable Affirm’s global growth.

What You’ll Do

• Own and deliver quarterly goals for your team, leading engineers through ambiguity to solve open-ended problems.
• Collaborate with product management, design, and analytics by participating in ideation, articulating technical constraints, and partnering on decisions that consider risks and trade-offs.
• Proactively identify and lead in solving project, process, technology, or business issues.
• Support operations and availability by creating and monitoring metrics, escalating when needed, and supporting on-call efforts.
• Foster a culture of quality and ownership by setting or improving code review and design standards.
• Help develop talent on your team by providing feedback and guidance, and leading by example.

What We Look For

• You have 4+ years of experience designing, developing, and launching backend systems at scale using languages like Python or Kotlin.
• Experience with highly available distributed systems using technologies like AWS, MySQL, and Kubernetes.
• Experience defining a technical plan for significant features or system components with an elegant, simple, and extensible design.
• Proficient at making significant changes in a large codebase, with a suite of tools and practices to enable safe changes.
• Take ownership of your growth, proactively seeking feedback from your team, manager, and stakeholders.
• Strong verbal and written communication skills for effective collaboration with a global engineering team.