Fibe Backend Engineer Interview: Rounds, Questions and Preparation

What the job involves

As a backend engineer in neobanking, lending, or insurtech, you build and maintain the server-side systems that power digital financial products, such as loan origination, credit decisioning, payment processing, and customer onboarding. Day to day, you write APIs, design database schemas, integrate with third-party financial services, and ensure high availability, security, and compliance with regulations. You also work closely with product, data, and risk teams to ship features that directly impact loan disbursals, repayments, and user experience.

Role and Technical Knowledge

1. 1

   Explain how you would design a REST API for a loan application submission.

   Cover endpoint structure, request/response payloads, validation, status codes, and idempotency. Mention how you would handle partial applications and document uploads.

2. 2

   What are the key considerations when integrating a payment gateway for loan repayments?

   Discuss webhooks, retries, idempotency, reconciliation, PCI compliance, and handling failures. Emphasize secure storage of transaction references and avoiding sensitive data in logs.

3. 3

   How would you model a database schema for tracking loan accounts, EMIs, and repayments?

   Talk about tables for customers, loans, schedules, transactions, and relationships. Mention indexing, foreign keys, and how to handle multiple part-payments or prepayments.

4. 4

   What is the difference between authentication and authorization in a banking backend?

   Explain authentication verifies identity (e.g., JWT, OAuth) and authorization controls access (e.g., RBAC, scopes). Give examples like a customer viewing only their loans versus an admin viewing all.

Practical Scenarios

1. 5

   A loan disbursement API is timing out during peak hours. How would you debug and fix it?

   Check logs, database queries, external service calls, and resource usage. Suggest optimizations like caching, async processing, rate limiting, and horizontal scaling. Mention monitoring and alerting.

2. 6

   How would you ensure data consistency when a customer makes a repayment and the loan balance is updated?

   Discuss transactions, ACID properties, and possibly distributed transactions or sagas if multiple services are involved. Mention idempotency keys and reconciliation jobs.

3. 7

   You need to implement a feature to calculate late payment fees. How would you approach it?

   Clarify business rules, design a configurable fee structure, and write unit tests. Consider time zones, holidays, and audit trails for regulatory compliance.

4. 8

   What steps would you take to secure sensitive customer data like bank account numbers?

   Talk about encryption at rest and in transit, tokenization, masking in logs, access controls, and compliance with RBI guidelines or similar regulations.

System Design and Scalability

1. 9

   Design a system for credit decisioning that pulls data from multiple bureaus and returns a decision in under 2 seconds.

   Outline microservices, caching, parallel API calls, fallback mechanisms, and asynchronous logging. Discuss how to handle bureau downtime and ensure auditability.

2. 10

   How would you architect a notification service to send SMS and email alerts for loan due dates?

   Cover queue-based processing, third-party integrations, retry logic, templating, and user preferences. Mention scalability and avoiding duplicate notifications.

3. 11

   What strategies would you use to handle a sudden spike in loan applications during a festival sale?

   Discuss auto-scaling, load balancing, database read replicas, caching, and rate limiting. Mention graceful degradation and monitoring key metrics.

Behavioural and HR

1. 12

   Why do you want to work in fintech, specifically in lending or insurtech?

   Show passion for financial inclusion, technology-driven solutions, and solving real problems. Relate to personal experiences or projects and mention the impact of neobanking.

2. 13

   Describe a time you had to learn a new technology quickly for a project.

   Use STAR method: situation, task, action, result. Highlight resourcefulness, online courses, documentation, and applying it successfully under a deadline.

3. 14

   Tell me about a time you worked in a team to solve a complex problem.

   Focus on collaboration, communication, and your specific contribution. Emphasize how you handled disagreements and achieved a shared goal.

4. 15

   How do you handle tight deadlines and pressure in a fast-paced environment?

   Give an example of prioritizing tasks, breaking down work, and staying calm. Mention tools like Trello or Jira and the importance of clear communication with stakeholders.