Course Overview
An API is not a technology. It is an agreement: here is an address, ask it this way, and this is the shape of what comes back. Every payment gateway, every courier tracking page, every "sign in with" button and every mobile app is that same agreement, kept.
This course teaches both sides of it. You build an API other people can rely on — predictable URLs, honest status codes, real authentication, a document that explains it — and you learn to consume someone else’s without your application falling over the first time theirs does.
You need to be able to write code in some server language. The examples use Node and Express; the ideas are the same in PHP, Python or Java.
What You’ll Learn
✅ HTTP properly: methods, status codes, headers, and why choosing the right one is most of API design.
✅ REST design: resources, naming, filtering, pagination, and consistent responses.
✅ Building: endpoints, validation, error shapes, and layered code you can still test.
✅ Security: API keys, JWTs, OAuth 2.0, CORS, rate limiting, and what never goes in a URL.
✅ Documentation: OpenAPI, examples, versioning, and deprecating without breaking anyone.
✅ Integration: calling third-party APIs, retries, timeouts, webhooks and idempotency.
✅ Testing and monitoring: Postman collections, automated checks, logs that help at 2am.
The Chapters
1 — What an API actually is. Client and server, contracts, and why the same data can serve a web page, a mobile app and a partner. You can explain an API to someone non-technical without using the word "endpoint".
2 — HTTP, in detail. Methods, safe and idempotent, status code families, headers, content types. You can pick the right method and the right status code without guessing.
3 — Designing resources. Nouns not verbs, nesting, collections and items, query parameters, pagination and filtering. You can write the full URL list for an application before building any of it.
4 — Requests and responses. JSON bodies, consistent envelopes, dates, nulls, and what to leave out. Two different endpoints of yours return errors in the same shape.
5 — Building the endpoints. Routing, controllers, services, and keeping the database out of the route handler. You can add an endpoint without copying an existing one.
6 — Validating input. Schema validation at the boundary, useful messages, 400 versus 422. Your API rejects a malformed request before it reaches your business logic.
7 — Authentication. API keys, sessions, JWTs, refresh tokens, and OAuth 2.0 flows in plain language. You can protect an endpoint and explain who is allowed through it and why.
8 — Authorization and abuse. Scopes and roles, ownership checks, rate limiting, CORS. You can stop a valid token from doing something it should not.
9 — Documenting the contract. OpenAPI, examples, and documentation generated from the thing it describes. Someone who has never met you can call your API from your document alone.
10 — Versioning and change. Breaking versus non-breaking changes, versioning strategies, deprecation. You can add a field without breaking a client that shipped last year.
11 — Consuming other people’s APIs. Reading a third-party document, keys and secrets, timeouts, retries with backoff, webhooks, idempotency. You can integrate a payment or messaging provider and survive their outage.
12 — Testing, deploying, watching. Postman collections, automated tests, environments, logging and monitoring. You find out your API is failing before your users tell you.
Course Highlights
🔥 Both directions — you build one and you consume one.
🔥 Security is chapters seven and eight, not a footnote.
🔥 A written contract at the end — an OpenAPI document, not just working code.
🔥 Free, including the test and the certificate.
Who Should Enroll?
- Developers who can build a site and now need it to talk to something else.
- Full-stack developers who want their back end used by more than one client.
- Anyone integrating payments, logistics or messaging and tired of guessing.
The Test and Certificate
The exam covers all twelve chapters: HTTP semantics, status codes, resource design, auth flows, CORS, idempotency and versioning. Register, take the hall ticket, sit the timed paper, and pass to earn a certificate carrying your name, the course and the date.
Sit it now, free: take the practice test for this course. It is scored in your browser and is a self-assessment, not a proctored exam.
Course Duration
📅 6 weeks, twelve chapters, practical. Free.
🚀 Build the interface other people’s software talks to.
Keywords
free API development course, RESTful API design, API integration, OAuth and JWT authentication, OpenAPI documentation, webhooks, rate limiting, free API certificate
