Intermediate · 5h 26m · 21 lessons
APIs
How apps talk to each other — endpoints, methods, status codes, and JSON.
What you'll learn
- ✦Explain what an API is, what REST means and why apps use APIs
- ✦Choose the right HTTP method for a task and tell safe methods from idempotent ones
- ✦Read a status code and a JSON response and say what happened
- ✦Build requests with path and query parameters, headers and a JSON body
- ✦Send authenticated requests with API keys and bearer tokens, and keep them secret
- ✦Design clean REST resources with clear errors, pagination and versioning
- ✦Call APIs from code and handle webhooks, CORS and failures safely
- ✦Compare REST with GraphQL, and use caching, tests and docs to make an API reliable
Part of these career paths
- Backend Developer path · course 5 of 14
- Full-Stack Developer path · course 4 of 14
Certification projects
Build 4 projects to earn your certificate
Hands-on work that proves you can apply what you learned — part of the certificate requirements.
Syllabus
Module 1 · 1h 21m
REST foundations Free
What you'll be able to do
- Can explain what an API is, and what makes an HTTP API RESTful and stateless
- Can choose the right method for a task and say which methods are safe or idempotent
- Can read a status code and say who has to fix the problem
- Can write valid JSON and spot the mistakes that stop it parsing
Module 2 · 1h 38m
Working with APIs Locked
What you'll be able to do
- Can name endpoints for collections and items, and choose path or query parameters
- Can build a request with the right method, headers and JSON body
- Can send an API key or bearer token safely and tell a 401 from a 403
- Can send requests in the console and read the status, headers and JSON that come back
Module 3 · 1h 3m
Designing good APIs Locked
What you'll be able to do
- Can design predictable resource URLs where the method carries the verb
- Can return the right status code with a consistent, helpful error body
- Can decide when a change needs a new version, and page through a long list
- Can respond to a 429 by waiting and backing off, and explain why rate limits exist
Module 4 · 43m
Calling & integrating APIs Locked
What you'll be able to do
- Can call an API with fetch, check res.ok before reading the JSON, and decide whether a failed call needs a fix or a retry
- Can explain how a webhook differs from polling, and plan a handler that replies fast and skips repeated events
- Can tell whether two URLs share an origin, and fix a CORS error on the API side
Module 5 · 41m
Beyond REST & reliability Locked
What you'll be able to do
- Can compare REST with GraphQL and gRPC, and count the requests a screen needs in each style
- Can use Cache-Control and ETags to skip downloads, and say when a saved copy is reused
- Can list the tests an endpoint needs and explain what an OpenAPI description gives callers