Walmart Low Level Design Round Interview Questions Asked in 2026

Design an in-memory credit-card payment system that processes transactions through multiple gateways such as Stripe and PayPal.

Support registering, enabling, and disabling gateways; preferred-gateway selection with a deterministic fallback; idempotent transaction IDs; full refunds; and transaction-status queries without exposing complete card numbers.

Design a deterministic simulation of a thread-pool executor with named logical workers, reusable threads, a bounded FIFO task queue, keep-alive expiration, and graceful shutdown.

Support multiple rejection policies, individual worker shutdown, task execution in steps, and stable event ordering while clearly modelling executor, worker, and task states.

Design an ATM that supports account creation, loading cash, card insertion, PIN authentication, balance checks, cash deposits and withdrawals, session cancellation, and card ejection.

Handle permanent blocking after three failed PIN attempts, exact withdrawals using the fewest available notes, supported denominations, atomic balance and cash updates, and invalid method-call order.

Design a movie-ticket booking system with cinemas in multiple cities, multiple screens per cinema, scheduled movie shows, and seat booking.

Users should be able to find cinemas showing a movie in their city, list relevant shows for a cinema, and book one or more seats while preventing concurrent double booking.

Design an in-memory rate limiter in which each resource has its own strategy and limits. Support both fixed-window-counter and sliding-window-counter algorithms.

Structure the solution so that more rate-limiting strategies can be added without changing the existing resource-management code.

Design a food-ordering and rating system similar to Zomato, Swiggy, DoorDash, or Uber Eats. The same food item may be offered by multiple restaurants.

Users should be able to order food, rate completed orders, fetch the highest-rated restaurants, and find the highest-rated restaurants for a specific food item.

Design a payment gateway that selects a payment strategy at runtime and delegates the request to payment-specific processing logic.

Support UPI and bank-transfer payments, validate their different detail formats, return deterministic results for invalid inputs, and keep the flow extensible for adding new payment methods.

Design and implement a live news feed in which providers publish articles under topics such as sports, technology, and finance. Users subscribe to topics, receive near real-time notifications, and fetch a personalized feed.

Make the system extensible for future ranking, filtering, muting, and pagination. A user should receive at most one notification for an article even when that article belongs to multiple subscribed topics.

Design a real-time order notification system for an e-commerce platform. Customers, sellers, and delivery partners subscribe to order events and receive notifications through channels such as email, SMS, and app push.

The design should support new event types and channels, different preferences for every stakeholder-event subscription, and replay using the stakeholder's latest active preferences.

Design an interface for submitting and managing workflows. A workflow contains one or more tasks and can run sequentially or in parallel.

The output of one workflow may become the input of another connected workflow. Each configured task receives a list of strings, applies its operations in order, and returns another list of strings.

Design a system with warehouses and stores. Each store maps to one warehouse, while a warehouse may serve many stores.

Whenever inventory is added to a warehouse, every mapped store must automatically receive the latest cumulative quantity for that product. The design should keep this synchronization clean and extensible.