OpenAI published a customer case study stating that travel tech company Holiday Extras used Codex to rebuild a functional application version within two weeks. The case study revealed that the conversion rate of the main application from opening to completing a booking increased by 32.5% compared to the older version, and the error rate dropped from 19% to 9%. These results are based on a comparison between the old and new versions of the application across different periods. The aforementioned figures represent the business performance disclosed in this customer case study.