Every API Explained: REST, GraphQL, gRPC, WebSockets & Webhooks

Every time you check the weather, pay online or log in with Google, dozens of programs quietly talk to each other through APIs. But there isn't just one kind of API. In this video we meet every major type, and see exactly how each one talks, using everyday analogies: a service window with a menu, a certified letter, a custom order form, a shared codebook, an open phone call, a radio station and a doorbell. In this video: • What an API really is: a contract, and a window in a wall • APIs without the internet: library functions and system calls • How web APIs talk: HTTP requests and responses, status codes (200, 404, 500) and JSON • REST: resources, GET / POST / PUT / DELETE, and why stateless scales • SOAP: XML envelopes and strict contracts (still big in banks and airlines) • GraphQL: one address, and exactly the fields you ask for • gRPC: Protocol Buffers, compact binary and streaming over HTTP/2 • Real time: polling vs WebSockets vs Server-Sent Events (how AI chat streams its answers) • Webhooks: when the server calls you • API keys, OAuth tokens and rate limits (429 Too Many Requests) • The API map: choose any API with two simple questions ⏱ CHAPTERS 00:00 Programs talking to programs 00:26 What is an API? The service window 01:03 APIs without the internet: libraries & system calls 01:37 How web APIs talk: HTTP, status codes, JSON 02:23 REST: the counter with a menu 03:06 SOAP: the certified letter 03:32 GraphQL: the custom order form 04:09 gRPC: the shared codebook 04:45 Real time: polling, WebSockets, Server-Sent Events 05:29 Webhooks: don't call us, we'll call you 05:59 API keys, OAuth tokens and rate limits 06:28 The API map: every style in one picture 07:06 Every API in one breath 📚 SOURCES & FURTHER READING • Roy T. Fielding, "Architectural Styles and the Design of Network-based Software Architectures", doctoral dissertation, UC Irvine, 2000 (chapter 5: REST). • W3C: SOAP Version 1.2 and WSDL 1.1. • GraphQL Foundation: graphql.org (specification, and the history of GraphQL at Facebook). • grpc.io documentation, and protobuf.dev (Protocol Buffers encoding). • IETF: RFC 9110 (HTTP Semantics), RFC 6455 (The WebSocket Protocol), RFC 6585 (429 Too Many Requests), RFC 6749 (OAuth 2.0). • WHATWG HTML Living Standard: Server-sent events. • MDN Web Docs: HTTP, WebSockets API, Server-sent events. Note: strictly speaking, REST is an architectural style, SOAP is a protocol and GraphQL is a query language. Here they are compared as what they all are in practice: ways for two programs to talk. The byte sizes shown for JSON vs Protocol Buffers are for one small example message. ▶ Watch next: • What Is Bio Computing? — https://youtu.be/8jFJ5K1Ob9Y #API #WebDevelopment #Programming