We have paused the creation of OAuth client IDs while we evaluate existing 3rd party usage of iRacing's APIs and SDK. When creation of OAuth client IDs is enabled again, we will post on our forums and include a mention in the release notes.
OAuth Client Id Creation — iRacing Forums
Complete documentation of the OAuth setup can be found at Introduction - iRacing.com Auth Service.
Discussion of the /data API can be found at:
Note that the /data API endpoint is NOT the same API as used by the sim for local telemetry logging, also referred to as the iRacing SDK. Discussion on the sim API can be found at: