Software Engineer - Backend & Checkout Services

At Affirm, we are reinventing credit to make it more honest and friendly, offering consumers transparent, flexible buy-now-pay-later (BNPL) payment options without hidden fees or compounding interest.

As a Backend Software Engineer on the Checkout Platform team, you will play a key role in designing and scaling the core financial engines that manage every transaction processed by Affirm. In this hands-on engineering role, you will build out microservices, RPC interfaces, and high-performance REST/gRPC APIs using Python and Kotlin. You will partner closely with product leaders and senior technical leads across the company to enhance the speed, availability, and resilience of the checkout user journey—ensuring millions of consumers enjoy a seamless, transparent buying experience.

Key Responsibilities

• Checkout Engine Engineering: Design, build, and maintain high-concurrency microservices and API interfaces managing checkout workflows and financial product delivery.
• System Performance & Reliability: Identify performance bottlenecks across checkout pipelines; optimize database queries, caching strategies, and service latency to improve system uptime.
• Architectural Component Ownership: Take ownership of key checkout system components, maintaining their operational health, monitoring, and long-term maintainability.
• Cross-Functional Collaboration: Partner with product managers, frontend engineers, and infrastructure leads to translate financial product requirements into scalable technical designs.
• Engineering Excellence: Drive high code quality standards through constructive code reviews, comprehensive testing, robust documentation, and knowledge sharing.

Requirements

Technical Stack & Software Engineering Depth

• Proven track record of developing, testing, and shipping high-quality, production-grade backend software at scale.
• Hands-on experience building REST/gRPC APIs, microservices, and distributed backend systems.
• Proficiency with Affirm's core tech stack or equivalent tools:
  • Backend Languages: Python, Kotlin, or Java/C++
  • Data & Caching: MySQL (or relational databases), Redis
  • Protocols & Cloud: RPC, AWS cloud services, Git/GitHub
• Strong understanding of software engineering best practices, system observability, and defensive software design.

Soft Skills & Work Logistics

• Customer-Centric Mindset: Empathetic approach to user experience and a passion for building reliable, honest financial tools.
• Strong Ownership & Collaboration: Clear verbal and written communication skills with a habit of over-communicating technical trade-offs and project status.
• Located and authorized to work in the United States or Canada (excluding Quebec).

Preferred Qualifications

• Direct domain experience working on high-throughput e-commerce checkout pipelines, payment gateways, or transactional financial platforms.
• Experience with high-availability microservice orchestration and low-latency distributed caching patterns.
• Familiarity with CI/CD deployment pipelines, automated integration testing, and canary deployments.

Total Rewards & Benefits

• 100% Employer-Paid Healthcare: Comprehensive medical, dental, and vision coverage with 100% of premiums covered for employees and their dependents.
• Equity & Stock Purchase Plan: Employee Stock Purchase Plan (ESPP) allowing team members to purchase Affirm stock at a discount.
• Flexible Work & Stipends: Remote-first working model with monthly stipends for home office setups, tech gear, and health/wellness expenses.
• Time Off & Onboarding: Flexible time off, generous holiday schedules, and an interactive in-person onboarding experience.