Senior Software Engineer, Backend (Identity International)

Affirm’s Identity team 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 Identity for all markets outside North America, playing a key role in Affirm’s international expansion. We are responsible for KYC, user lifecycle management, and identity decisioning across multiple regulatory environments. This work is about shaping how Affirm adapts its core Identity platform to new market dynamics, customer expectations, and compliance requirements.

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. You should be comfortable designing across system boundaries, driving collaboration with partner teams, and advocating for technical investments that improve long-term execution. We’re looking for someone who takes ownership beyond shipping code: raising code quality and review standards, making performance, availability, and scale tradeoffs explicit, and improving the operational health of the systems they own. You’ll help reduce toil, create useful playbooks, mentor engineers, support new hires and interns, and contribute to high-signal hiring.

Most importantly, we’re excited to work with someone who leaves things better than they found them, communicates clearly across audiences, uses customer feedback to influence technical plans, and helps the team continuously improve.

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, ship impactful features, investigate complex production issues, and keep 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

· 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.


What We Look For

· You have 4+ years of experience designing, developing and launching backend systems at scale using languages like Python or Kotlin.
· You have a track record of developing highly available distributed systems using technologies like AWS, MySQL and Kubernetes.
· 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.

Pay Grade - N
Equity Grade - 5

Base pay is part of a total compensation package that may include monthly stipends for health, wellness and tech spending, and benefits (including 100% subsidized medical coverage, dental and vision for you and your dependents). In addition, the employees may be eligible for equity rewards offered by Affirm Holdings, Inc. (parent company).

GBR base pay range per year: £120,000–£168,000 GBP

Location - Remote UK

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