OpenAI claims its team built the Sora Android app in just 28 days by leveraging its code-generation AI, Codex. According to a report from OpenAI employees Patrick Hum and RJ Marsan, a small team of four engineers utilized an early version of the GPT-5.1 Codex model to build the application, processing around five billion tokens along the way.
According to the authors, the AI handled the bulk of the actual writing—specifically tasks like translating existing iOS code into Android-compatible formats. This allowed the human developers to focus on high-level architecture, planning, and verifying the results. The team described Codex as acting like a new, experienced colleague that just needed clear instructions to get the job done. Despite the rapid timeline, OpenAI reports the app is 99.9 percent stable. You can read a detailed breakdown of their process on the OpenAI blog.
