Sharing my experience going through Confluent’s interview loop for an SDE role. The rounds were a good mix of algorithmic depth, API-level design, and real-world engineering conversations. Here's the full breakdown:
Round 1: Phone Screen (DSA)
Problem:
Given a list of function signatures and a list of input arguments, return all matching functions based on parameter compatibility.
Follow-up:
Extend the solution to handle variadic arguments like Integer... args.
Focus was on type matching and signature parsing.
Round 2: DSA
Problem 1: Check if a given Sudoku board is valid (partial board).
Problem 2: Solve a complete Sudoku puzzle.
Emphasis was on clean recursion, backtracking, and pruning optimization.
Round 3: High-Level Design (Podcast Service)
Topic: Design a Podcast Service with:
- Feed view
- Subscribe/Unsubscribe to podcasts
- Add podcasts and episodes
Note:
No architecture diagram was expected. Focus was on:
- API design (verbs, response codes, headers) - This is key, if you do any mistake they highlight it as if the world has ended.
- SQL queries
- Data modeling
Round 4: High-Level Design (TempMail Service)
Topic:
Design a TempMail generation service where generated emails are valid for 5 hours.
Discussion focused on:
- Expiry mechanism
- Storage strategies
- Access control and validation
- Building sensible mail names
Round 5: DSA / Code Debugging
Problem:
Given an implementation of Quicksort, identify and fix bugs.
Then optimize performance by discussing and applying pivot strategies to reduce the chance of hitting O(n²).
Strategies covered:
- Randomized pivot
- Dual pivot
- Median-of-three approximation
Round 6: Culture & Value Fit
Topics Discussed:
- Going above and beyond to exceed customer expectations
- Taking initiative in challenging situations
- Pushing back on legacy decisions and suggesting improvements
- Mentoring and enabling peers to succeed
- Handling ambiguity and overcoming complexity in large-scale systems
Final Thoughts
Overall it takes more than 2 months. Be patient.
Confluent’s loop is a good blend of:
- Deep technical discussions
- For SSE2, one strong hire is mandatory in design rounds.
- Behavioral rounds that go beyond standard LPs and into actual engineering stories
If you're preparing, focus on clean APIs, SQL/data modeling, and be ready to defend trade-offs.
Verdict: Overall Lean No Hire. I got all strong hires in coding rounds but no strong hire in design round. Though, personally I felt it went well. Apparently a few negatives outweighed a lot of positives. But it is what it is.
YoE: 10.7 Years
