3GPP 5G APIs OpenAPI specifications

3GPP OpenAPI specs define OAuth 2.0 clientCredentials auth with service-specific scopes. The specs reference a token endpoint at {nrfApiRoot}/oauth2/token for SBA APIs and also allow unauthenticated access in some cases via an empty security requirement. 3GPP itself publishes the specifications, not a single public token-issuing developer console. To use this in practice, obtain OAuth client credentials from the network/service provider implementing the specific 3GPP API you are integrating with, then request a token from that provider's OAuth server as described by the relevant spec files in OpenAPIs for the Service-Based Architecture and the published OpenAPI documents such as TS29520_Nnwdaf_AnalyticsInfo.yaml or TS24558_Eees_EASDiscovery.yaml.