Index Ai Academy
Phase 8 of 12 · about 10 hours of study

APIs

Design, build, secure and scale web APIs from first principles. 13 lessons, about 10 hours of study, in four tracks. One lesson is free to try without an account: the first, HTTP from the wire up. The rest need a free account.

Start with HTTP from the wire up Create a free account

What you'll learn

HTTP from the wire up · 2 lessons, about 1.5 hours

  1. HTTP from the wire up FreeWhat really travels between client and server: bytes, headers and bodies.
  2. API stylesREST, RPC, GraphQL, gRPC and streaming: what each is for.

Building APIs · 5 lessons, about 4 hours

  1. Build an API server from scratchRouting, handlers and responses, with no framework.
  2. A web framework, from the insideDecorators, middleware and error handling: how Flask and FastAPI work.
  3. Designing a REST APIResources, methods, status codes, errors and pagination done well.
  4. Validating requests with schemasCheck every request against a JSON Schema and say exactly what's wrong.
  5. A database-backed APICRUD endpoints on SQLite, with safe concurrent updates.

Security & reliability · 3 lessons, about 2.5 hours

  1. Authentication and authorizationAPI keys, sessions, tokens and OAuth: who's calling, and what may they do?
  2. Rate limits, retries and idempotencyKeep an API up under load and make retries safe.
  3. Webhooks and eventsPush events to other systems: signed, retried and deduplicated.

Design at scale · 3 lessons, about 2.5 hours

  1. Documenting APIs with OpenAPIA machine-readable contract for docs, SDKs and AI tools.
  2. Running APIs in productionVersioning, CORS, caching, request ids and health checks.
  3. Capstone: a complete APIAn authenticated, validated, paginated API with tests.

Before you start

Lessons here build on earlier phases:

The placement test can mark off what you already know, so you only study what's new to you.

What you'll build

A complete API

An authenticated, validated, paginated API with tests. Read the tutorial.

  • Design a small API end to end: resources, routes, schemas, errors and auth
  • Combine authentication, scopes and object-level checks on every endpoint
  • Wire validation, persistence, cursor pagination and idempotency into one service

When you finish

Finish every lesson in this phase, or show you know it in the placement test, and you earn a certificate of completion, "APIs (Phase 8)", with its own link you can share.