Holiday Extras Rebuilds Mobile App with OpenAI Codex

Travel technology business Holiday Extras rebuilt its main mobile app in two weeks using OpenAI Codex, achieving development progress that previously would have taken over six months, according to OpenAI.

The rebuild yielded a 32.5% increase in open-to-book conversion on the main app. At the same time, the app error rate fell from 19% to 9%, marking a 10% reduction in app error rate.

Holiday Extras previously relied on an annual release schedule for major changes to its main app. Following the rebuild, the company shifted to weekly releases in the first month, with each release delivering multiple new features. For its Countdown app, development accelerated from adding a feature roughly every six months to making multiple additions a week.

Company-wide ChatGPT Enterprise access established the foundation for Holiday Extras, while Codex extended into building software. CEO Matthew Pack builds with Codex himself to understand what colleagues need. Across the business, employees apply operational knowledge directly to their tools, including an accountant who rebuilt finance systems around his business understanding and feedback from colleagues.

Liam Thompson, VP of AI Innovation, worked with engineers to translate customer understanding into software. Small, documented packages created reusable foundations, while engineers focused on architecture, APIs, security, and development workflows. Codex also enabled iOS and Android features to be developed together.

Customer feedback connects directly into software updates under the new workflow. When a Countdown customer complained about a missing list view, an agent prepared a fix, Thompson approved it, and the submitted update led the customer to change a one-star review to five stars. An automated system also converts airport-transfer customer chats into actionable tickets to identify supplier problems, while Thompson's dot tool prepared a performance report after an app launch.