OAuth 2.0 Authorization Code Grant: What it is & how it works

OAuth 2.0 is the industry-standard protocol for authorization, allowing applications to securely access user data without handling passwords. Among its grant types, the Authorization Code Grant is most robust and widely used for web applications, involving a two-step flow suitable for apps that can securely store a client secret. This flow involves requesting user consent, handling a redirect with an authorization code, and exchanging that code for tokens via trusted authorization servers. The Protocol now requires PKCE (Proof Key for Code Exchange), initially an extension for public clients like mobile apps, to prevent authorization code interception attacks. PKCE binds the authorization request and token exchange using a code challenge and verifier, bolstering security even for server-side apps. OAuth 2.1 mandates PKCE for all clients to enhance security across platforms, making the Authorization Code Grant a secure choice for web, mobile, and desktop applications.