Uniphore Technologies Backend Engineer Interview: Rounds, Questions and Preparation

What the job involves

Backend engineers in Indian SaaS and B2B product companies build the server-side logic, APIs, and data pipelines that power multi-tenant platforms used by enterprise customers. Day to day, you will write code in languages like Java, Python, or Go, design REST or gRPC APIs, work with databases and message queues, and ensure the system scales securely across many client organisations. You will also debug production issues, participate in code reviews, and collaborate with frontend, DevOps, and product teams.

Role and technical knowledge

1. 1

   What is multi-tenancy in a SaaS backend, and how would you isolate data between customers?

   Explain shared database with tenant ID column versus separate schemas or databases. Mention trade-offs in cost, complexity, and security, and give a simple example of filtering queries by tenant ID.

2. 2

   How would you design a REST API for a B2B product that lets clients create and fetch support tickets?

   Cover resource naming, HTTP methods, status codes, pagination, authentication with API keys or OAuth, and versioning. Show awareness that enterprise clients need stable, documented APIs.

3. 3

   Explain the difference between SQL and NoSQL databases. When would you choose one for a SaaS product?

   Discuss schema flexibility, transactions, scaling patterns, and consistency. Give a concrete example like using PostgreSQL for billing records and a document store for flexible event logs.

4. 4

   What happens when a user types a URL and hits enter, from the backend perspective?

   Walk through DNS, TCP handshake, HTTP request, load balancer, application server, database query, and response. Keep it structured and mention caching or CDN where relevant.

Practical scenarios and problem solving

1. 5

   A customer reports that their API calls are timing out during peak hours. How would you debug this?

   Start with logs, metrics, and tracing. Check database slow queries, connection pool limits, thread exhaustion, and external service latency. Suggest short term fixes like caching and long term fixes like horizontal scaling.

2. 6

   You need to add a new feature to an existing backend service without breaking current clients. How do you approach it?

   Talk about backward compatible API changes, feature flags, versioning, writing tests, and staged rollout. Show that you understand enterprise clients cannot upgrade instantly.

3. 7

   How would you handle a background job that processes thousands of records and sometimes fails midway?

   Mention idempotency, retries with exponential backoff, dead letter queues, checkpoints, and logging. Explain how to avoid duplicate processing and how to alert on repeated failures.

4. 8

   Your service depends on a third party SMS gateway that goes down. What do you do?

   Suggest circuit breakers, fallback providers, queueing messages for later, and graceful degradation. Show that you think about user experience and business continuity.

Coding and data structures

1. 9

   How would you find the first non-repeating character in a string?

   Use a hash map to count frequencies in one pass, then scan again to find the first character with count one. Mention time and space complexity.

2. 10

   Given a list of API request logs, how would you find the top 5 most frequent endpoints?

   Use a hash map to count occurrences, then a min-heap of size 5 or sort the entries. Discuss handling large files by streaming instead of loading everything into memory.

3. 11

   Write a function to merge two sorted lists into one sorted list.

   Use two pointers and compare elements one by one. Explain edge cases like empty lists and duplicate values, and state O(n plus m) time complexity.

4. 12

   How would you detect a cycle in a linked list?

   Describe Floyd's tortoise and hare algorithm with two pointers. Mention O(n) time and O(1) space, and explain why it works.

Behavioural and HR questions

1. 13

   Tell me about a time you had to learn a new technology quickly for a project.

   Use the STAR method. Focus on the steps you took, the resources you used, and the outcome. Show curiosity and ability to self learn, which matters in fast moving SaaS teams.

2. 14

   Describe a situation where you disagreed with a teammate. How did you handle it?

   Show that you listen, discuss with data or logic, and commit to the team decision. Avoid blaming others and highlight a positive resolution.

3. 15

   Why do you want to work in a B2B SaaS product company rather than a consumer app company?

   Talk about interest in solving complex enterprise problems, working with multiple stakeholders, and building reliable systems. Mention that you enjoy depth over superficial scale.

4. 16

   Where do you see yourself in three years as a backend engineer?

   Show a growth path from writing features to owning services and mentoring juniors. Align your goals with learning system design, cloud, and domain knowledge in SaaS.