Bing announced version 13 of the Bing Ads APITrack this API in April of 2019. With that announcement came the warning of version 12’s demise, which was scheduled for October 31, 2019. That time has come and past. Bing is now notifying developers that all version 12 endpoints will soon return error 303 (ApiVersionNoLongerSupported).
Version 12 endpoints will begin returning error 303 starting in February 2020 and Bing is encouraging all developers to migrate to V13 immediately to avoid service interruption. The company has a migration guide that it hopes will assist developers in the transition. Bing also offers language-specific guides for getting started with the API that include C#, Java, PHP, and Python.
Bing also provides a great guide for getting started with using the OAuth 2.0 protocol for Bing Ads API authentication.