Affirm interview questions and how to prepare

1. You are building a new feature for Affirm's 'Buy Now, Pay Later' (BNPL) product that allows users to split their purchase into 0% interest installments over 3 months. A significant percentage of users are dropping off during the application flow when asked for their Social Security Number (SSN). Design a system to identify potential fraud without relying on SSN for initial approval, while maintaining regulatory compliance and user trust. Consider the trade-offs between fraud detection accuracy and user friction.

   Software EngineerSystem DesignTests: Evaluates system design skills, understanding of trade-offs, and awareness of financial industry constraints.

2. Affirm processes millions of transactions daily. Imagine a scenario where the processing time for a new loan application has suddenly increased from an average of 500ms to 5 seconds. What are the potential causes of this latency increase, and how would you systematically debug this issue in a distributed system environment, focusing on microservices related to credit underwriting and payment processing?

   Software EngineerDebuggingTests: Assesses debugging methodology, knowledge of distributed systems, and ability to identify bottlenecks.

3. Affirm's core product involves assessing credit risk for users making purchases. Write a Python function that simulates a simplified credit scoring model. This function should take user attributes (e.g., credit history length, debt to income ratio, purchase amount, merchant type) and return a risk score. Discuss how you would handle edge cases and potential biases in this model.

   Software EngineerCoding ReasoningTests: Tests coding proficiency, algorithmic thinking, and understanding of financial risk assessment principles.

4. Affirm offers 'Pay in 4' and longer-term installment plans. Consider the real-time event stream of loan originations. How would you design a system to detect and alert on unusual spikes in application approvals for a specific merchant, which could indicate a coordinated fraud attempt or a sudden surge in demand that might strain Affirm's capital?

   Software EngineerSystem DesignTests: Evaluates ability to design real-time monitoring and alerting systems for financial applications.

5. Affirm's engineering team uses a microservices architecture. You are tasked with refactoring a monolithic service responsible for user authentication and loan application submission into smaller, independent services. Describe the challenges you anticipate, the strategy for breaking down the monolith, and how you would ensure data consistency and seamless user experience during the transition.

   Software EngineerSystem DesignTests: Probes system design capabilities in the context of microservice migration and distributed system challenges.

6. Affirm's 'Interest-Free Instalment Plans' are a core product. Imagine you're building a feature to dynamically adjust the available repayment terms (e.g., 3, 6, 12 months) based on a user's creditworthiness and the merchant's risk profile. Outline the technical considerations for implementing this dynamic term selection, including data sources, real-time decisioning, and API design.

   Software EngineerSystem DesignTests: Tests understanding of building flexible and dynamic financial product systems.

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