Step through OAuth 2.0 authorization flows visually with token exchange diagrams and parameter details.
OAuth 2.0 Flow Visualizer turns an authorization flow into an ordered conversation among the browser, client, authorization endpoint, and token endpoint. Each step shows the request or response parameters attached to that hop, helping distinguish redirects from the later token exchange and showing where PKCE values belong. A common surprise is that an authorization-code redirect does not contain an access token. It returns a temporary code to the client, which exchanges that code at the token endpoint. With PKCE, the challenge and verifier appear in different steps.
Advancing through the diagram follows the browser from the client to the authorization endpoint and back to the registered redirect URI. Parameter details let you track values such as client_id, redirect_uri, response_type, scope, and state in their protocol roles. In a PKCE case, code_challenge and its method belong on the authorization request; the authorization code belongs on the redirect back.
After authorization, the visual sequence isolates the token request from browser redirects. In an authorization-code PKCE exchange, the client sends the code, a redirect_uri when required, and code_verifier to the token endpoint. A successful response includes an access token and token type; expiry information and a refresh token are not guaranteed. Reading these as separate hops prevents front-channel and token-endpoint parameters from being conflated.
The client starts with a fresh code_verifier and forms code_challenge from it, normally using the S256 method. Only the challenge travels in the authorization request. The original verifier is supplied when the code is redeemed, allowing the authorization server to reject a captured code when the redeemer cannot prove possession of that verifier.
No. It can clarify the message sequence and expose incorrect assumptions about parameter placement, but choosing a flow also depends on the client type, its ability to protect credentials, provider capabilities, redirect environment, and threat model. Confirm the final design against the provider's documentation and current OAuth security guidance.
The behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.
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