Salesforce System Design Questions

Design a scalable coffee ordering notification system

Design a coffee ordering system for a single shop that later grows into a chain of stores. Customers browse the menu, customize drinks, pay, and order for pickup or in-store; baristas work an order queue and move orders through…

Also reported as: Design a coffee ordering system

Design an analytics dashboard for an AI chat app

Design the backend for an internal analytics dashboard for a ChatGPT-like conversational AI product, used by product managers and engineers. It should show metrics such as daily and monthly active users, conversations and…

Also reported as: Design a Chat Analytics Backend

Track Top-K Frequent Elements from an Unbounded Stream

Design a system that continuously computes the top K items from a very large event stream: for example the K most-viewed URLs, the K services with the most error logs in the last 5 minutes, the top 100 most active users in a…

Design an Idempotent Payment Processing Platform

Design a payment processing system (like Stripe's core) that handles about 10,000 transactions per second between merchants and external payment providers. Support the full lifecycle: authorization (place a hold on funds with low…

Design a Scalable Notification Service

Design a multi-channel notification service (push, email, SMS, in-app) that other services call to notify users. It must accept sudden bursts of millions of notifications with low acknowledgement latency, persist them durably,…

Design a Venue Rental and Booking System (HLD)

Design a hotel or rental booking system like Booking.com or Airbnb. Users search listings by location and date range with filters, view availability and a price quote, book a room or property, and cancel; hosts manage listings,…

Design a Synchronized Watch Party System (LLD)

Design (low-level, object-oriented) a synchronized watch party system where multiple users watch the same video together: play, pause and seek actions by the host (or anyone) are reflected on every participant's player,…

Design a Multi-Tenant Enterprise Messaging System

Design a real-time chat system like WhatsApp or Slack supporting one-to-one and group conversations (and, for Slack variants, workspaces, channels and threaded replies). Users send and receive messages with low latency, see…

Design a TikTok-like short video platform

Design a video platform like YouTube, Netflix or TikTok. Creators upload videos (or a catalog is ingested); videos are transcoded into multiple resolutions and bitrates; viewers stream them reliably worldwide with adaptive…

Design a configurable monthly API rate limiter

Design a distributed rate limiter that protects APIs by limiting requests (or consumed units such as LLM billing tokens or storage quota) per user, API key, tenant, or IP. It must support configurable rules (e.g., 100…

Design a pipeline orchestration system on Kubernetes

Design a distributed job scheduler that runs user-defined jobs at a specified time (one-time) or on a recurring cron schedule, at a scale of millions of jobs per day. Requirements: jobs fire close to their scheduled time, each…

Design a file sync and sharing service

Design a file (or photo) storage and sync service like Dropbox, Google Drive or iCloud Photos. Users upload files from one device and see them on all devices; they can share files and folders, keep versions, and work offline with…

Design a Concurrent Car Reservation Service

Design a car rental reservation service. Customers search for available cars at a location for a time interval, place a temporary hold on a car, confirm or cancel the reservation, and view their bookings. Requirements: no two…

Design a Multi-Vendor Integration Platform

Design a platform that connects a product to many third-party vendors (email providers, Slack/Teams, CRMs). A customer authorizes a vendor account (OAuth), and the product can then invoke vendor actions (send a message, create a…

Design a collaborative spreadsheet backend

Design a real-time collaborative editor like Google Docs or Google Sheets. Multiple users view and edit the same document or spreadsheet concurrently, see each other's changes and cursors in real time, and the document converges…

Design a 911 emergency calling service

Design a 911 emergency calling and routing platform. Users place emergency calls from mobile, landline or VoIP devices; the system determines the caller's location, routes the call to the correct emergency response center (PSAP),…