Oa2

OA2 is an acronym used in several domains, but in information technology it most commonly denotes OAuth 2.0, a standard for delegated authorization used by many web and mobile APIs.

OAuth 2.0 defines a model with four main roles: the resource owner, the resource server, the client, and the authorization server. Clients obtain access tokens from the authorization server to access protected resources on behalf of a user or service. The framework supports multiple grant types, including authorization code, client credentials, the resource owner password credentials (password) grant, and device authorization. Access tokens are typically bearer tokens, and their lifetimes and scopes constrain what resources can be accessed. For public clients, the use of PKCE (Proof Key for Code Exchange) is recommended to enhance security during the authorization code flow.

OAuth 2.0 has been widely adopted to authorize API access across major platforms. It is not itself an authentication protocol, though OpenID Connect builds on OAuth 2.0 to provide authentication information alongside authorization data.

The OA2 acronym can also refer to other concepts in different domains, such as open access initiatives or internal versioning schemes. Because OA2 has multiple possible meanings, the intended referent is usually determined by the surrounding context. If in doubt, consult the applicable documentation or specifications to confirm which OA2 is intended.