OAuth 2.0 is a standard that apps can use to provide client applications with secure delegated access. OAuth works over HTTPS and authorizes devices, APIs, servers, and applications with access tokens rather than credentials. OIDC adds a signed ID token and a UserInfo endpoint.| Okta Developer
The OAuth 2.0 Playground lets you play with OAuth 2.0 and the APIs that supports it.| developers.google.com
OpenID Connect Core 1.0 incorporating errata set 2| openid.net