Confluent interview process (2026)

Round-by-round breakdown of the Confluent software engineering interview across 4 levels and 18 rounds: interview mode, sample questions, and worked solutions.

Confluent salary & ratings · All interview processes

Software Engineering Intern (6-month, final-year students)

Difficulty: Medium · Timeline: Campus/off-campus cycle typically runs Aug-Dec for a January · Recommended prep: 6-8 weeks · Cooldown: ~6-12 months

  1. Round 0: Online Coding Assessment (HackerRank)

    Assessment · 75 minutes · difficulty 3/5 · elimination round

    Mode of interview: Online assessment · HackerRank

    Sample question: Time-Based / Windowed Key-Value Store — Design a time-based key-value store. set(key, value, timestamp) stores the value at the given timestamp; get(key, timestamp) returns the value whose stored timestamp is the largest one that is <= the query timestamp (empty string if none). Timestamps for a key are strictly increasing. Confluent variants layer on TTL expiry / a running windowed average of the non-expired values.

  2. Round 1: Technical / DSA Interview (live coding)

    Onsite · 45 minutes · difficulty 3/5 · elimination round

    Mode of interview: Onsite or virtual onsite interview

    Sample question: Insert Delete GetRandom O(1) — Design a data structure supporting insert(x), remove(x), and getRandom() each in average O(1). insert returns false if x already present, remove returns false if x absent, and getRandom returns a currently-stored element uniformly at random. Confluent frames the reported variant as an 'infinite queue with GetRandom in O(1)'.

  3. Round 2: System Design / Concurrency Round

    System_design · 45-60 minutes · difficulty 3/5 · elimination round

    Mode of interview: Live system design interview

    Sample question: Design a Thread-Safe LRU Cache with TTL — Design and implement an LRU cache exposing get(key), put(key, value), and size(). Achieve O(1) get/put using a hash map plus doubly linked list. Confluent's intern/campus round then layers on (a) TTL expiry of stale entries and (b) thread-safety with no concurrent execution across get/put/size — discuss the locking strategy (mutex vs. reader-writer/semaphores) and the starvation/fairness of the synchronization mechanism.

  4. Round 3: HR / Behavioral Round

    Behavioral · ~25 minutes · difficulty 1/5

    Mode of interview: Live behavioral interview

Software Engineer (New Grad / SDE-I, campus & early-career, India)

Difficulty: Hard · Timeline: 3-5 weeks · Recommended prep: 6-10 weeks · Cooldown: ~6-12 month

  1. Round 0: Online Assessment (HackerRank)

    Assessment · ~70 minutes · difficulty 3/5 · elimination round

    Mode of interview: Online assessment · HackerRank

    Sample question: Valid Sudoku — Given a fully or partially filled 9x9 Sudoku board (empty cells marked '.'), determine whether the current state is valid: no digit repeats within any row, any column, or any 3x3 sub-box. Only the filled cells are checked; the board need not be solvable. Read 9 lines of 9 characters and print 'true' or 'false'.

  2. Round 1: DSA / Coding Interview

    Phone · ~45-60 minutes · difficulty 3/5 · elimination round

    Mode of interview: Remote phone or video interview

    Sample question: Sudoku Solver — Given a partially filled 9x9 Sudoku board (empty cells '.'), fill every empty cell so that each row, column, and 3x3 box contains the digits 1-9 exactly once. Use recursive backtracking with constraint pruning. Read 9 lines and print the solved 9x9 board. Follow-up interviewers push on pruning and clean recursion.

  3. Round 2: Concurrency / Low-Level Design Interview

    Onsite · ~60 minutes · difficulty 4/5 · elimination round

    Mode of interview: Onsite or virtual onsite interview

    Sample question: Design a Thread-Safe Bounded Cache (LRU) — Design and implement a thread-safe fixed-capacity cache exposing get(key), put(key,value) and size(), where no two operations may run concurrently on shared state, with no starvation. Discuss the reader/writer problem, evolve from a naive 'turn' variable to a semaphore/lock-based solution, and reason about O(1) eviction with a hashmap + doubly linked list.

  4. Round 3: HR / Behavioral Round

    Behavioral · ~30-45 minutes · difficulty 1/5

    Mode of interview: Live behavioral interview

Senior Software Engineer (SSE / SSE-II, lateral, Bengaluru / Remote India)

Difficulty: Hard · Timeline: 3-5 weeks · Recommended prep: 8-12 weeks · Cooldown: ~6-12 months

  1. Round 0: Recruiter Screen

    Phone · ~30-60 minutes · elimination round

    Mode of interview: Remote phone or video interview

  2. Round 1: Qualifier Technical Phone Screen (DSA + concurrency/LLD)

    Phone · ~60 minutes · difficulty 3/5 · elimination round

    Mode of interview: Live interview · CoderPad

    Sample question: Design a Globally Distributed, Read-Optimized Key-Value Store at Scale — Design a globally distributed, read-optimized key-value store (Kafka-adjacent): data partitioning/sharding, replication and consistency model (strong vs eventual), leader/follower reads, hot-key handling, cache tiers, and how to sustain high-throughput streaming writes with reliable, low-latency reads across regions.

  3. Round 2: Onsite Loop — Coding / DSA

    Onsite · ~45-60 minutes · difficulty 3/5

    Mode of interview: Onsite or virtual onsite interview

    Sample question: Windowed Average over a Time-Based Key-Value Store (TTL cache with get_average) — Implement a key-value store where each entry has a timestamp and expires after a fixed EXPIRY window. Support put(ts,key,val), get(ts,key) (return the value if the latest entry for key is not expired at time ts, else -1), and avg(ts) returning the average of all currently non-expired values. Timestamps stream in increasing order; prune before serving. Follow-ups probe strongly- vs eventually-consistent concurrent access.

  4. Round 3: Onsite Loop — System Design (distributed systems / data streaming)

    System_design · ~60 minutes · difficulty 4/5

    Mode of interview: Live system design interview

    Sample question: Design a Temporary / Disposable Email Service — Design a receive-only disposable email service that mints auto-expiring inbox addresses, ingests inbound SMTP mail, stores messages with TTL, exposes an inbox API/UI, and garbage-collects expired addresses and mail. Cover addressing scheme, storage + expiry, MX/SMTP ingestion path, spam/abuse handling, and scale.

  5. Round 4: Onsite Loop — Additional Coding / LLD + Engineering Values

    Onsite · ~45-60 minutes · difficulty 3/5

    Mode of interview: Onsite or virtual onsite interview

    Sample question: Design an RSS / Podcast News-Feed Aggregator (Feedly-like) — Design a feed aggregator: users subscribe to RSS/podcast sources, the system polls/ingests sources, dedups and stores article/episode metadata, and generates a ranked personalized feed. Cover subscribe/unsubscribe API + data model, ingestion scheduling and fan-out, dedup, feed generation (pull vs push), and scaling reads.

  6. Round 5: Hiring Manager / Behavioral Round

    Behavioral · ~30-45 minutes · difficulty 1/5

    Mode of interview: Live behavioral interview

Staff Software Engineer (Staff / SSE-2 lateral, Bengaluru / Remote India)

Difficulty: Hard · Timeline: 4-6 weeks · Recommended prep: 8-12 weeks · Cooldown: No published policy. LOW confidence — unverified.

  1. Round 0: Recruiter Screen

    Phone · ~30-45 minutes · elimination round

    Mode of interview: Remote phone or video interview

  2. Round 1: Technical Phone Screen (DSA + concurrency)

    Phone · ~60 minutes · difficulty 3/5 · elimination round

    Mode of interview: Live interview · CoderPad

    Sample question: Word and Phrase Search in Documents — Given a set of documents (each a sequence of words), support phrase queries: for a query phrase, return the indices of all documents that contain the phrase as a contiguous run of words. Read D documents (one per line), then Q query phrases; print matching document indices per query, or NONE. Follow-ups push toward an inverted index / positional index for scale.

  3. Round 2: Onsite Loop — System Design (heavy) + Coding + LLD

    System_design · ~60 minutes · difficulty 4/5

    Mode of interview: Live system design interview

    Sample question: Design a URL Shortener at Scale — Design a URL shortener (bit.ly-style): short-code generation (hashing/base62/counter), collision handling and uniqueness, read-heavy redirect path with cache/DB sharding, custom aliases, analytics, and back-of-the-envelope capacity math (RPS, storage, servers). Cover reliability and horizontal scaling.

  4. Round 3: Engineering Values / Leadership + Hiring Manager

    Behavioral · ~45 minutes · difficulty 2/5

    Mode of interview: Live behavioral interview

Other companies' interview processes

Worked sample solutions (code, design diagrams, and STAR answers) for every round are available in the FAANGPlus app: open interview processes.