Senior Software Engineer, Back-end – Fraud

Affirm

Senior Software Engineer designing real-time fraud decisioning services at Affirm. Collaborating with global teams to ensure operational efficiency in fraud management.

Posted 7/20/2026full-timeRemote • 🇵🇱 PolandSenior💰 PLN 308,000 - PLN 428,000 per yearWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates expertise in building scalable backend systems using Python or Kotlin, with a strong focus on system design and integration of AI-driven solutions. Proven ability to lead teams through ambiguity while fostering a culture of quality and ownership.

Highest-signal resume keywords

Python DevelopmentKotlin DevelopmentAWS InfrastructureSystem DesignAI-Driven Engineering

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

Backend Systems DevelopmentSQL ProficiencyDistributed SystemsMachine Learning IntegrationCI/CD Practices

Soft Skills

Strong Communication SkillsProactive MindsetTeam Leadership

Tools & Technologies

MySQLPostgreSQLKubernetesSnowflakeAirflow

Industry Keywords

Fraud PreventionRisk SystemsReal-Time DecisioningFintech SectorInternationalization

Tech Stack

Tools & technologies

AirflowAWSDistributed SystemsKotlinKubernetesMySQLPostgresPythonSQL

About the role

Key responsibilities & impact

Own and deliver quarterly goals for your team, leading engineers through ambiguity.
Design and implement real-time fraud decisioning services and APIs in Python or Kotlin.
Build and evolve the platform to launch fraud decisioning in a new country quickly.
Integrate region-specific fraud and risk vendors and operationalize machine learning and AI signals.
Support peers and stakeholders across the product development lifecycle.
Monitor metrics and contribute to keep-the-lights-on and on-call efforts.
Foster a culture of quality and ownership within the team.

Requirements

What you’ll need

5+ years of experience building backend systems at scale using Python or Kotlin.
Experience with distributed systems and infrastructure using AWS, MySQL/PostgreSQL, and Kubernetes.
Strong system design skills and a track record of delivering maintainable, extensible services.
Fluency with AI-driven engineering.
Proficiency in SQL and working with data-rich environments.
Familiarity with CI/CD practices and safe production deployments.
Strong written and verbal communication skills, especially in distributed teams.
A proactive, ownership-driven mindset with a focus on learning and team success.
Experience with Snowflake, dbt, Airflow, or Chronosphere (nice to have)
Background in fraud prevention, risk systems, or real-time decisioning (nice to have)
Experience building for multiple markets or regions - internationalization or localization (nice to have)
Experience working in the fintech sector or other highly regulated environments (nice to have).

Benefits

Comp & perks

100% subsidized medical coverage, dental and vision for you and your dependents
Flexible Spending Wallets for tech, food and lifestyle
Away Days - wellness days to take off work and recharge
Learning & Development programs
Parental benefits
Employee Resource & Community Groups