If you just want your credit report the official site is (https://www.annualcreditreport.com/) which looks fishy but is real (https://www.consumer.ftc.gov/articles/free-credit-reports). I am not aware of any more authoritative source or any API.

>Only one website — AnnualCreditReport.com — is authorized to fill orders for the free annual credit report you are entitled to under law.

From the FTC page