OAuth 2.0 flows

What a session covers

The tutor works through these with you, in conversation and code. A session ends when you have shown them, not when a video does.

1. Explain what OAuth 2.0 lets a user grant and what it does not
2. Trace the authorization code flow with PKCE step by step
3. Spot the implicit flow or the missing state check

In practice

A few lines that show OAuth 2.0 flows doing its job.

1. App sends the browser to the provider's /authorize with client_id,
   redirect_uri, scope, state and a PKCE code_challenge.
2. User signs in and consents.
3. Provider redirects back with ?code=...&state=...
4. App checks state, then POSTs code + code_verifier to /token.
5. Provider returns access_token (and maybe refresh_token).
6. App calls the API with Authorization: Bearer <access_token>.

The common mistake

What to know first

Your roadmap puts these before OAuth 2.0 flows, unless you already know them.

• Authentication providers

How it stays learned

Once a session shows you understand OAuth 2.0 flows, it comes back for review. Each review takes a minute and tells the memory model how well you still know it.

1. Day 3First recall, while it is fresh
2. Day 7Second, a week on
3. Day 18Last, when it has settled

Where it leads

Topics that build on OAuth 2.0 flows.

• JWT validation
• OpenID Connect