System Design

⏱ 6 min read Core Entities Driver: driver_id, name, vehicle_type (ECONOMY/COMFORT/XL), status (OFFLINE, AVAILABLE, ON_TRIP), current_location (POINT: lat/lng), last_location_update, rating, acceptance_rate. Rider: rider_id, name, […] Read article

⏱ 5 min read Core Challenge and Entities A flash sale creates a sudden traffic spike (100x-1000x normal load) competing for limited inventory. The Read article

⏱ 6 min read Requirements and Core Challenge Functional: multiple users edit the same document simultaneously, changes from all users are reflected in real Read article

⏱ 8 min read Scope and Requirements A payment processing platform handles money movement between buyers and sellers through external payment processors (Stripe, Adyen, Read article

⏱ 10 min read Problem Statement Design a content moderation system for a social platform. User-generated content (text, images, video) must be screened before Read article

⏱ 6 min read Core Entities Provider: provider_id, name, email, type (DOCTOR, THERAPIST, CONSULTANT, TUTOR), timezone, settings (JSONB: buffer_minutes_between_appointments, max_advance_days, min_notice_hours, auto_confirm). Schedule: schedule_id, Read article

⏱ 6 min read Requirements and Scale Functional: upload raw video, transcode to multiple resolutions (240p/480p/720p/1080p/4K), store and serve video streams, support adaptive bitrate Read article

⏱ 6 min read Core Entities Product: product_id, sku, name, category_id, unit_cost, unit_weight_grams, dimensions (JSONB: length, width, height in mm), reorder_point, reorder_quantity, lead_time_days, is_active. Read article

⏱ 6 min read Core Entities Ticket: ticket_id, title, description, status (OPEN, IN_PROGRESS, PENDING, RESOLVED, CLOSED), priority (P1/P2/P3/P4), category (BUG, FEATURE, INCIDENT, QUESTION, CHANGE), Read article

⏱ 5 min read Requirements and Scale Functional: real-time score updates ( millions of simultaneous reads). Read-to-write ratio: 100,000:1. The core challenge is fan-side Read article

⏱ 5 min read What is a Knowledge Graph? A knowledge graph stores entities (nodes) and typed relationships (edges) between them. Examples: Google Knowledge Read article

⏱ 5 min read Core Entities User: user_id, name, email, role (EMPLOYEE, MANAGER, ADMIN), hourly_rate (default), timezone, created_at. Project: project_id, name, client_id, status (ACTIVE, Read article

⏱ 5 min read Requirements and Scale Functional: shorten long URLs, redirect short URLs to originals, track click analytics (count, geography, device, referrer), support Read article

⏱ 5 min read Core Entities Survey: survey_id, creator_id, title, description, status (DRAFT, ACTIVE, PAUSED, CLOSED), settings (JSONB: allow_anonymous, one_response_per_user, show_progress_bar, randomize_questions, response_limit), start_date, Read article

⏱ 7 min read Core Entities Poll: poll_id, creator_id, question, poll_type (SINGLE_CHOICE, MULTIPLE_CHOICE, RANKED, RATING), status (DRAFT, ACTIVE, CLOSED), is_anonymous, allow_change_vote, visibility (PUBLIC, PRIVATE, Read article