APIs
8 topics in apis.
What is an API
API design is a core skill for backend engineers and a key topic in system design interviews.
API Gateway
In a microservices architecture, clients should not need to know about individual service addresses.
REST vs GraphQL
Choosing between REST and GraphQL is a common API design decision and interview question.
WebSockets
WebSockets power real-time features: chat applications, live notifications, stock tickers, collaborative editing, and online gaming.
Webhooks
Webhooks enable event-driven integrations without continuous polling. They are used by virtually every SaaS platform (Stripe, GitHub, Slack, Twilio) to.
Idempotency
Network failures are inevitable. Clients will retry requests. Without idempotency, retries can cause catastrophic bugs — a payment system that charges.
Rate Limiting
Without rate limiting, a single client can overwhelm your service (intentionally via DDoS or unintentionally via a bug).
API Design Best Practices
APIs are contracts — once published, they are hard to change without breaking clients. Good design from the start saves years of technical debt.