⏱ 7 min read Core Entities PaymentIntent: intent_id (UUID), merchant_id, customer_id, amount (integer cents), currency, status (CREATED, PROCESSING, REQUIRES_ACTION, SUCCEEDED, FAILED, CANCELLED, REFUNDED), payment_method_id, […] Read article

⏱ 7 min read Core Responsibilities An identity service (also called an IAM or auth service) handles: Authentication (who are you?) — verifying credentials Read article

⏱ 7 min read Core Entities User: user_id, email, timezone, working_hours (JSON: {mon: “9:00-17:00”, …}). Calendar: calendar_id, user_id, name, color, is_primary, visibility (PRIVATE, PUBLIC, Read article

⏱ 7 min read Core Architecture A search system takes a text query and returns a ranked list of documents (web pages, products, articles). Read article

⏱ 7 min read Core Requirements A collaborative document editor allows multiple users to edit the same document simultaneously, with changes reflected in near-real-time Read article

⏱ 7 min read What is a Document Store? A document store (MongoDB, DynamoDB, Couchbase, Firestore) stores JSON-like documents with flexible schemas — each Read article

⏱ 7 min read Core Entities Event: event_id, name, venue_id, event_date, doors_open, start_time, status (ON_SALE, SOLD_OUT, CANCELLED, COMPLETED), total_capacity. Venue: venue_id, name, address, seating_map_url, Read article

⏱ 7 min read Requirements and Scale An analytics pipeline collects events from product surfaces (web, mobile, backend services), processes them in real time 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

⏱ 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