Flipkart Interview Questions & Answers 2026

Components: Pre-sale registration, queue management, inventory locking with optimistic concurrency, distributed cache (Redis) for product details, CDN for images, payment gateway with retry logic, async order confirmation. Handle: thundering herd, fair queueing, oversold prevention. Scale: millions of concurrent users.

Token bucket or sliding window log algorithm. Use Redis with Lua scripts for atomicity. Distributed coordination via consistent hashing of user ID. Handle: per-user limits, per-API limits, burst traffic, regional differences. Provide fallback to local rate limiter if Redis fails.

Components: API for trigger, message queue (Kafka), notification router, channel-specific services (Push - FCM/APNS, SMS - Twilio, Email - SES, In-app), user preference service, rate limiter, template engine, analytics. Handle: priority, batching, deduplication, retry with backoff, deliverability tracking.

Implement: get(key), put(key, value, ttl), delete(key). Use HashMap<String, Entry> where Entry has value, expiryTime. Handle TTL via lazy deletion (check on access) + background cleanup thread. Bonus: LRU eviction with DoublyLinkedList. Use ReadWriteLock for concurrency. 90 minute round.

Sliding window with HashMap storing char and last seen index. Move right pointer expanding window. If duplicate found, move left to max(left, lastSeen+1). Update max length. Time O(n), Space O(min(m,n)) where m is alphabet size.

PSP is Flipkart's commitment on delivery promise to customers. Backend: ML model predicts delivery time using product, seller, warehouse, customer location, courier capacity. Real-time updates based on order processing, dispatch, in-transit events. Critical for conversion (delivery promise affects checkout) and customer satisfaction.

Use STAR method. Describe junior's situation (struggling with code reviews, design), your approach (1:1s, pairing sessions, structured learning plan), challenges, and measurable outcome (improved velocity, promotion). Flipkart values strong engineering culture and mentorship.

Mention Flipkart's Indian DNA - deeper understanding of tier 2/3 markets, vernacular UX, focus on emerging consumer (Flipkart Wholesale, Shopsy). Tech challenges unique to India (low bandwidth, varied devices). Strong product culture, ownership at all levels. Walmart backing provides scale + autonomy. Diversity of work across e-commerce, payments, logistics.