Client and authorization server exchange an S256 challenge and browser-facing callback code through the browser. A separate token-endpoint lane exchanges code plus verifier for tokens. The client can be public or confidential.

OAuth code flow trades a code for a token

Authorization-code flow moves access-token delivery to the token endpoint rather than returning an access token in the browser-facing authorization redirect. That distinction reduces exposure in URLs, but does not mean a browser can never hold a token. The client architecture determines who exchanges the code and where the resulting credentials live. ...

October 20, 2027 · 5 min · XB Field Notes