What is an API? A plain-language guide to how APIs workWhat an API is, how REST APIs work over HTTP, the methods you'll actually meet — GET, POST, PUT, PATCH, DELETE — and how to read a response.HTTP request methods explained: GET, POST, PUT, DELETE & moreWhat HTTP request methods are, what each one does, and the difference between GET, POST, PUT, PATCH, DELETE and the rest — with safe vs idempotent.JWT explained: what a JSON Web Token is and how it worksWhat a JSON Web Token is, how the header.payload.signature structure works, which claims and algorithms exist, and how to validate JWTs safely.What are WebSockets? A plain explanationWebSockets keep a two-way connection between browser and server open, so either side can send data any time. Here's how the handshake, frames, and close codes work — and when to use them.What is a headless CMS? How headless content management worksA headless CMS keeps content separate from the site that shows it, exposing it through an API. Here's how headless CMS works, how it differs from a traditional CMS, and when to choose it.REST API design best practices: resource naming, HTTP methods, and status codesHow to design a clean REST API: plural resource URLs, safe and idempotent HTTP methods, meaningful status codes, pagination, and error responses — with practical examples.GraphQL vs gRPC: which API technology should you choose?GraphQL and gRPC are two modern ways to build APIs. GraphQL lets clients query exactly the fields they need over a single HTTP endpoint; gRPC calls typed remote methods over HTTP/2 with binary Protocol Buffers. Compare the trade-offs and learn when to choose each.How to handle errors in Node.js: try/catch, error-first callbacks, promises, and event emittersNode.js errors come in several asynchronous styles, and each has its own correct way to be caught. This guide explains try/catch for synchronous code, error-first callbacks, promise rejection handling, and the 'error' event for streams and event emitters.REST vs gRPC: which API style should you choose?REST and gRPC are two ways to build APIs. REST uses HTTP and JSON with universal browser support; gRPC uses HTTP/2 and Protocol Buffers for binary efficiency and code-generated stubs. Compare the trade-offs and learn when to choose each.What is an API Gateway? A practical guide for developersAn API gateway is a single front door for all client requests to your back-end services. This guide explains what an API gateway does, the problems it solves, common patterns, and how to choose one.What is CORS? Cross-Origin Resource Sharing explainedCross-Origin Resource Sharing (CORS) is the mechanism browsers use to allow or block requests between different origins. This guide explains how CORS works, why it exists, common errors, and how to fix them.What is GraphQL? How it works and when you should use itGraphQL is an open-source query language for APIs that lets clients request exactly the data they need. This guide explains how GraphQL works, its type system, queries and mutations, and how it compares to REST.What is JSON? The complete guide to JavaScript Object NotationJSON (JavaScript Object Notation) is an open, language-independent, text-based data interchange format derived from JavaScript object syntax. It represents data as a small set of types — objects, arrays, strings, numbers, booleans, and null — and is the de facto format for web APIs, configuration files, and data exchange between servers and clients. This guide explains JSON's syntax, its data types, how it compares to XML and YAML, and how to parse and generate it.How to add JWT authentication to a Node.js API: a practical guideStep-by-step implementation of JWT authentication on a Node.js/Express API: password hashing, login endpoint, token verification middleware, refresh tokens, and the common security pitfalls.What is OAuth 2.0? How OAuth works and how to secure itOAuth 2.0 is an open standard for delegated authorization defined in RFC 6749. It lets a user (the resource owner) grant a third-party application (the client) limited access to resources on another server without sharing their password. This guide explains the four roles, the main grant types, the recommended authorization-code flow with PKCE, and the security best practices from RFC 9700.What are Protocol Buffers? How protobuf works and when to use itProtocol Buffers (protobuf) is Google's language-neutral, platform-neutral data serialization format. Define your data once in a .proto file, compile it, and get fast, compact binary output. Learn how protobuf works and when it outperforms JSON.How to implement rate limiting in Node.js: algorithms and practical examplesRate limiting protects Node.js APIs from abuse and overload. This guide explains fixed window, sliding window, and token bucket algorithms, shows how to add rate limiting to an Express API, and how to test it.How to build a REST API with Node.js and ExpressLearn to create a production-ready RESTful API using Node.js and Express: setup, routing, middleware, environment variables, error handling, and deployment best practices — with a practical CRUD example for managing resources.REST vs GraphQL: which API style should you choose?REST and GraphQL are two ways to build web APIs. REST uses fixed endpoints and HTTP methods; GraphQL uses a single endpoint where clients query exactly the fields they need. Compare the trade-offs and learn how to choose.What is a webhook? How webhooks work and how to secure themA webhook is a user-defined HTTP callback: one service sends an HTTP request to a URL you control when an event happens. Learn how they work, how they differ from polling and regular APIs, and how to verify signatures and handle retries safely. 