PKCE (Proof Key for Code Exchange)
PKCE, short for Proof Key for Code Exchange, is an OAuth 2.0 extension that protects the authorization code flow for public clients like mobile apps and single-page applications. The client sends a hashed code challenge, then proves possession of the original verifier when exchanging the code for tokens.
Technical Architecture & Deep-Dive
Public clients cannot safely store a client secret, so an intercepted authorization code could be redeemed by an attacker. PKCE fixes this: the app generates a random code verifier, sends its SHA-256 hash as the challenge, and later presents the verifier. Only the original app can complete the exchange.
PKCE is now recommended for all OAuth clients, including server-side apps. It complements, rather than replaces, keeping provider API secrets out of client code.
Key Architectural Benefits
Implement PKCE (Proof Key for Code Exchange) at the Edge
Deploy lightweight API aggregation, edge caching, and secret injection in minutes without Docker containers or complex servers.
Frequently Asked Questions
Q:Does PKCE replace a backend for my mobile app?
No. PKCE secures user login flows. Calls to third-party APIs that require secret keys still need a server-side or edge proxy.
Related Architecture Concepts
OAuth 2.0 is an authorization framework that lets an application obtain limited access to a user account on another service without handling the user password. The user approves requested scopes, and the application receives an access token it uses to call the service API.
OpenID Connect (OIDC) is an identity layer built on OAuth 2.0 that lets applications verify who a user is. Alongside an access token, the identity provider issues a signed ID token, a JWT containing claims such as the user ID, email, and authentication time.
A Client Token is a scoped, revocable authentication credential designed for frontend web and mobile applications. It grants permission to invoke specific edge API pipelines while enforcing allowed-origin domains and rate limits, safely abstracting sensitive upstream API secrets.