Api

Api

What Is an API?

What it is

An Application Programming Interface — a contract that lets two systems talk to each other.

Request & Response

How it works

Types of APIs

Common types

REST — lightweight, HTTP-based

GraphQL — flexible, query-driven

gRPC — fast, binary protocol

WebSocket — real-time, persistent connection

Securing Your API

Auth

API Keys — simple token-based access

OAuth 2.0 — delegated authorization

JWT — stateless, signed tokens

API Design Principles

Design

Consistency — predictable naming and structure

Versioning — avoid breaking changes

Idempotency — safe to retry

Handling Errors Gracefully

Reliability

Return meaningful HTTP status codes. 4xx = client error. 5xx = server error. Always include a message.

Rate Limiting & Throttling

Scale

Protect your API from abuse. Cap requests per user, per minute. Return 429 Too Many Requests when exceeded.

Documentation Is the Product

Docs

Great APIs ship with great docs. Use OpenAPI / Swagger to auto-generate interactive references.

Build. Integrate. Ship.

Next steps

Good APIs unlock everything else.