Author name: techinterview.org

⏱ 4 min read What a Response Cache Does A response cache sits in front of upstream services and stores HTTP responses so that […] Read article

⏱ 4 min read The Distributed Scheduler Problem A scheduler that runs on a single node is a single point of failure. A scheduler Read article

⏱ 5 min read Coupon Schema A coupon service manages promotional codes that apply discounts to orders. The core schema: CREATE TABLE coupons ( Read article

⏱ 5 min read Promotion Schema A discount engine evaluates active promotions against a cart and computes the final discounted price. The promotion schema Read article

⏱ 6 min read Dependency Graph Construction An asset pipeline must understand the relationships between source files to build correctly. The dependency graph is Read article

⏱ 5 min read Core Schema The subscription manager tracks the relationship between users, plans, and billing periods. CREATE TABLE subscriptions ( subscription_id UUID Read article

⏱ 5 min read URL Scheme An image optimization service accepts transform parameters via URL and returns a processed image. A clean URL scheme Read article

⏱ 5 min read Preference Hierarchy A user preferences service must resolve the right value for any preference key given a user and device Read article

⏱ 5 min read Ingestion Flow A webhook ingestion service receives HTTP POST requests from third-party providers (Stripe, GitHub, Twilio) and delivers the events Read article

⏱ 5 min read Federation and Schema Ownership A GraphQL gateway unifies multiple microservice schemas into a single graph that clients query. Each service Read article

⏱ 5 min read Connection Lifecycle WebSocket connections begin as HTTP requests and upgrade to a persistent bidirectional channel: Client sends HTTP GET with Read article

⏱ 5 min read gRPC Fundamentals gRPC uses HTTP/2 as its transport and Protocol Buffers as its serialization format. Compared to REST+JSON: strongly typed Read article

⏱ 6 min read Quota Management Service: Low-Level Design A quota management service defines resource limits per customer or user, tracks real-time usage against Read article

⏱ 5 min read A/B Test Assignment Service: Low-Level Design An A/B test assignment service determines which experiment variant a user sees and guarantees Read article

⏱ 5 min read Experiment Logging Service: Low-Level Design The experiment logging service collects exposure and conversion events, computes metric values per variant, runs Read article