diff --git a/.env.example b/.env.example
index a31023a..5e69214 100644
--- a/.env.example
+++ b/.env.example
@@ -1,8 +1,24 @@
 # Database path (relative to project root or absolute)
 DATABASE_URL=./data/crumbs.db
 
-# Server origin (required for CSRF protection)
+# Server origin (required for CSRF protection and OAuth redirect URLs)
 ORIGIN=http://localhost:3000
 
 # Node environment
 NODE_ENV=development
+
+# --- OAuth Providers (optional, auto-enabled when set) ---
+
+# Google OAuth 2.0
+# AUTH_GOOGLE_CLIENT_ID=
+# AUTH_GOOGLE_CLIENT_SECRET=
+
+# GitHub OAuth
+# AUTH_GITHUB_CLIENT_ID=
+# AUTH_GITHUB_CLIENT_SECRET=
+
+# Generic OIDC (e.g. Authentik, Keycloak, Okta)
+# AUTH_OIDC_ISSUER=https://your-idp.example.com
+# AUTH_OIDC_CLIENT_ID=
+# AUTH_OIDC_CLIENT_SECRET=
+# AUTH_OIDC_DISPLAY_NAME=SSO