System Design

⏱ 7 min read Core Entities Cart: cart_id, user_id (nullable for guest), session_id (for guest carts), status (ACTIVE, MERGED, ORDERED), created_at, updated_at, expires_at. CartItem: […] Read article

⏱ 6 min read Core Requirements A coupon system allows businesses to issue discount codes that customers apply at checkout. Types: percentage discount (20% Read article

⏱ 6 min read Core Entities Customer: customer_id, name, date_of_birth, ssn_hash, address, kyc_status (PENDING, VERIFIED, REJECTED). Account: account_id, customer_id, account_type (CHECKING, SAVINGS, MONEY_MARKET), status Read article

⏱ 7 min read Why Audit Logs? An audit log records every significant action in a system: who did what, to which resource, when, Read article

⏱ 6 min read Core Entities Rider: rider_id, name, phone, email, payment_method_id, rating, total_trips. Driver: driver_id, name, phone, license_number, vehicle_id, status (OFFLINE, AVAILABLE, ON_TRIP), Read article

⏱ 6 min read The Flash Sale Problem A flash sale offers a limited quantity of items at a steep discount for a short Read article

⏱ 7 min read Core Requirements An inventory management system tracks the quantity of products across one or more warehouses, coordinates stock reservations during Read article

⏱ 7 min read Core Entities Workspace: workspace_id, name, owner_id, plan (FREE, PRO, ENTERPRISE), created_at. Board: board_id, workspace_id, name, description, visibility (PUBLIC, PRIVATE, WORKSPACE), Read article

⏱ 7 min read Core Entities Auction: auction_id, seller_id, item_id, title, description, start_price, reserve_price (nullable, minimum price to sell), buy_now_price (nullable, instant purchase), start_time, Read article

⏱ 7 min read Core Requirements A digital wallet holds a user’s balance and enables peer-to-peer transfers. Key operations: add money (top-up from a Read article

⏱ 7 min read Why Resilience Patterns? In a microservices architecture, service A calls service B which calls service C. If C is slow Read article

⏱ 7 min read Core Entities Course: course_id, title, description, instructor_id, category, level (BEGINNER, INTERMEDIATE, ADVANCED), language, price, published_at, status (DRAFT, PUBLISHED, ARCHIVED), total_enrolled. Read article

⏱ 7 min read Core Entities Restaurant: restaurant_id, name, address, lat, lng, cuisine_type, rating, is_open, prep_time_minutes (average). MenuItem: item_id, restaurant_id, name, description, price, category, Read article

⏱ 7 min read Overview An ad server matches advertisers’ ads to available ad slots on publisher pages in real time. The two main Read article

⏱ 6 min read Core Entities Hotel: hotel_id, name, address, city, star_rating, amenities (JSON), check_in_time, check_out_time. RoomType: room_type_id, hotel_id, name (STANDARD, DELUXE, SUITE), max_occupancy, Read article