Senior Software Engineer, Backend (Test Enablers) 100% remote)

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. We are looking for a highly motivated Senior Software Engineer to join our Test Enablers team within Test Platform Engineering (Developer Productivity). The Test Enablers team builds and operates the platforms that allow Affirm engineering teams to test with confidence. Our systems provide synthetic identities, test data seeding, mocking, deterministic testing workflows and load testing. Developer Productivity’s mission is to dramatically accelerate software development at Affirm while keeping our systems reliable for customers. Our long-term north star is to scale to 1,000 PRs per day by December 2027. To reach that goal, Affirm needs validation systems that are fast, trustworthy, automated, and scalable. This role is central to that effort. You will design and build platform capabilities that help engineers validate product changes earlier, run safer load tests, reduce reliance on expensive E2E-only validation, and improve the reliability of CI signals. You will also help prepare Affirm’s testing infrastructure for AI-assisted development workflows, where agents and humans need deterministic, observable, and actionable validation feedback. Affirm is growing fast, and we want you to help us scale our products and engineering systems 10x and beyond through world-class developer productivity infrastructure. What You’ll DoDesign, build, and maintain scalable systems for synthetic identities, test data seeding, mocking, load testing, and deterministic validation workflows. Help evolve Affirm’s testing strategy from broad E2E-heavy validation toward a more scalable model with stronger component, integration, contract, performance, and targeted E2E testing. Build platform capabilities that make production-like load testing safer, more repeatable, and easier to operate. Improve our test platform so it is reliable, observable, and easier for other teams to adopt. Partner with product engineering and infrastructure teams to improve test signal quality, reduce false failures, and support faster validation loops. Lead medium-to-large technical projects from ambiguous problem definition through design, implementation, rollout, and operational ownership. Improve reliability and operational maturity through dashboards, SLOs, alerts, runbooks, and clear ownership models. Reduce manual operational load for load testing, including test data creation, environment setup, reporting, and failure diagnosis. Write high-quality, maintainable code that can be easily understood and extended by others. Contribute to technical specs, RFCs, ADRs, project plans, and other async artifacts that align teams around technical decisions. Review code and technical designs, provide constructive feedback, and help raise engineering standards. Mentor engineers and help build a culture of practical testing excellence. What We Look For5+ years of software engineering experience. Strong backend engineering experience with Python, Kotlin, Java, or similar languages. Experience designing, building, and operating distributed systems, platform infrastructure, internal developer tools, or testing infrastructure. Strong ownership and ability to independently drive ambiguous technical work to completion. Experience improving system reliability, observability, operational maturity, and maintainability. Ability to collaborate across engineering teams and influence technical direction through clear communication. Excellent written and verbal communication skills, including async artifacts such as technical specs, RFCs, ADRs, and project plans. Strong engineering fundamentals across system design, testing, debugging, reliability, and production operations. Operational ownership of critical internal testing platforms, including reliability, observability, alerting, runbooks, and incident readiness. Experience with test automation frameworks, test data systems, mocks, contract testing, integration testing, load testing and CI/CD platforms. Ability to balance pragmatic delivery with long-term technical quality. Passion for improving developer productivity and product quality through scalable, automated, reliable systems. Total rewardsWe believe the people building honest financial products at Affirm should share in its success. That's why our total rewards are designed to support your health, growth, financial well-being, and future. In service of our mission, we reward employees through a combination of base pay, equity (from parent company), and comprehensive benefits. Base Pay Grade - N308 000 zł - 428 000 zł Base pay ranges and placement within those ranges are determined based on several factors, including role, experience, and job-related skills. In addition to base pay, all employees in this role are eligible to receive equity from the parent company each year. This means as Affirm’s parent company grows, employees have the opportunity to share in that growth financially. Equity Grade - 4 (awarded in US Dollars)Affirm Holdings, Inc. Equity Grade exampleEquity grade: 4New hire equity: $32,000-$48,000Annual Refresh: $10,000Reward equity: $0-$150,000Affirm also provides flexible spending wallets to all employees for technology and wellbeing related needs, which are reimbursable up to 1390 zł per month. In addition to your compensation, our comprehensive benefits are designed to support you and the people who matter most. Benefits include: Competitive paid time off, paid public holidays, and additional paid Away Days to rest and recharge. Comprehensive private healthcare through Lux Med's Platinum package. A MultiSport card to support your health and well-being. Learning and development programs to help you grow professionally. Family healthcare support through Maven and parental leave support through Parentaly. Mental well-being support through Lyra, including up to 12 confidential counseling or coaching sessions each year for you and your household members. Financial well-being support through Northstar, with unlimited access to Certified Financial Advisors and planning tools at no cost to you. Employee Resource Groups (ERGs) that foster connection and inclusion. Eligibility for creative tax benefits, subject to applicable law, role, and company policy. Location - Remote PolandThe majority of our roles can be located anywhere in Poland. This job description is not a contractual document, and is not intended to have binding force.#LI-Remote