Flipkart system design interview questions

Which levels get a design round

Design questions candidates report

• Task scheduler assigning tasks to worker threads (machine coding)

  How to design a shared scheduler that runs millions of one-off and cron jobs on time: a jobs table indexed by next run time, partitioned schedulers that claim due work with leases, a unique run key so each tick fires once, a queue and worker pool with heartbeats, retries, timeouts and fencing tokens, and the midnight thundering herd, priorities and per-team quotas.

  Full walkthrough: Job scheduler

• Food ordering system (machine coding)

  How to design a food delivery platform that connects customers, restaurants and couriers: requirements, dinner-peak math, the order and tracking APIs, an order state machine with idempotent payments, ingesting courier GPS pings into an in-memory geo index, dispatch that scores and offers orders to couriers with timeouts and batching, ETAs from prep time and travel time, and the trade-offs.

  Full walkthrough: Food delivery

• Notification system

  How to design a shared notification service that any team can call: one API for push, SMS, email and in-app, user preferences and quiet hours, templates, separate priority queues so a marketing blast never delays a login code, per-provider rate limits, retries with backoff, deduplication, dead device tokens, bulk campaign fan-out and delivery tracking.

  Full walkthrough: Notification system

• Ledger for transactions from many services

  Design the payment service behind an online store, where the hard part is never charging twice and never losing money. Requirements and scale, the payments API and data model, then the hard parts: idempotency keys end to end, the payment state machine, unknown outcomes after timeouts and webhooks, a double-entry ledger, daily reconciliation with the provider, tokenization to stay out of card data, and the trade-offs.

  Full walkthrough: Payment system

• Flash-sale inventory at big-sale scale

  Design a sale where ten thousand phones go on sale at noon and ten million people click at once. Requirements and a burst of millions of requests a second, the claim API and data model, why one inventory row melts, then the hard parts: a filtering funnel at the edge, atomic stock claims in Redis with split buckets, asynchronous order creation through a queue, payment windows that return stock and reconciliation.

  Full walkthrough: Flash sale

Also reported

• Interview slot scheduling system (machine coding)

How to answer any design question: the LADDER method · How the design round is scored by level · Low-level design and machine coding

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