Uber Low Level Design and Depth in Specialization Round Interview Questions from 2026

Design an in-memory publish/subscribe system with exactly one global FIFO (first in first out) queue. Multiple publishers can publish messages to this queue. Many subscribers can subscribe to the same queue. When a message is appended, all subscribers are notified, and each subscriber consumes at its own pace. A subscriber can consume only those messages which were sent while it was subscribed. This question requires the use of Observer pattern (Queue Manager = Subject, Subscribers = Observers).

Design and implement an in-memory unix filesystem shell that supports three commands: - mkdir <path>, - pwd, and - cd <path> (with a special wildcard segment *).

Design a parking lot system that supports parking and removing vehicles. The parking lot has multiple floors. Each floor has a list of parking spots.

Floors are numbered from 0. Spots on each floor are also numbered from 0 from left to right. Initially, all parking spots are empty.

The parking lot should always assign the lowest available valid spot. A lower floor is preferred first. If multiple valid spots are available on the same floor, the spot with the lower index should be assigned first.

Design a customer visit tracking service for a website that receives millions of visits every day. Each customer has a unique identifier that remains the same across all their visits.

A customer is a one-time visitor if they have visited exactly once so far. A customer is a recurrent visitor if they have visited more than once.

The service should record customer visits, return a customer's latest login timestamp, and return the first customer who is still a one-time visitor.

Design a lightweight expense-sharing system that tracks how much each person owes or is owed after group expenses are split evenly among participants. The system maintains net balances and exposes operations to add users, record expenses, and list simplified debtor-to-creditor balances.

Design a voting system for a multiple-choice question with exactly 4 options. When a user clicks one option, that option receives one vote. After every vote, the system should return the updated vote percentage for all options. The percentage of each option also represents how much color fill should be shown for that option in the UI. For example, if an option has 40% votes, then 40% of that option row should be filled with color.

You are designing an Uber Eats ads dashboard where an advertiser can choose when an ad should run during a week. The dashboard has 7 days, from Monday to Sunday. Each day is divided into 6 fixed time slots of 4 hours each. A selected slot means the ad will be displayed during that slot for that day. Clicking a slot toggles it. If the slot was not selected, it becomes selected. If it was already selected, it becomes unselected. The dashboard stores the full weekly schedule together. Switching between days should not require fetching separate data for that day.

Design an Uber Eats pricing calculator for food orders. Each food item has a price based on its size, and customers may add toppings. The final price can be affected by BOGO offers, surge pricing, coupon discounts, and an extra Uber One member discount. All prices are represented in cents. Return the final payable amount as an integer number of cents.

Design a circuit breaker that protects a service when too many requests arrive in a short time. This circuit breaker opens based on the number of requests, not the number of failed requests. The breaker has three states: CLOSED, OPEN, and HALF_OPEN. Requests are accepted only when the current state allows them.

Design a key-value store that supports insertion, lookup, deletion, and access to the first and last active entries in constant time.

Active entries are maintained in insertion order. Updating an existing key changes only its value and does not change its position.

Design a simple Meeting room reservation System for a fixed list of conference rooms. You will be given the room identifiers up front, and you must support booking and canceling meetings while ensuring no two meetings overlap in the same room.

Write code for low level design of a movie ticket booking system like BookMyShow. System has cinemas located in different cities. Each cinema will have multiple screens, and users can book one or more seats for a given movie show.

System should be able to add new cinemas and movie shows in those cinemas. Users should be able to list all cinema's in their city which are displaying a particular movie. For a given cinema, users should also be able to list all shows which are displaying a particular movie.

Build an in-memory leaderboard for a fantasy-sports style app. Each user creates exactly one team made up of one or more players. As a live match progresses, players receive positive or negative points. A user’s score is the sum of the current scores of all players on that user’s team. You must support querying the Top-K users ranked by score.

Design a system that manages assignment of trains to platforms in a railway station and supports time-based queries, with a clean, extensible object-oriented design.