Apps Built With OpenAI Codex: 9 Revenue-Backed Businesses, and Why Each Uses a Second Agent
9 revenue-backed businesses build with OpenAI Codex, from a $1M ARR dialer to a 17-year-old's $30K/mo SaaS. How they use it, and why never alone.
Very few revenue-backed businesses build with OpenAI's Codex alone, and that is the useful finding. The ProvenStartups index holds 9 businesses whose own interviews say Codex helps build or run the product. Every one of them also uses another AI coding tool or agent, such as Claude Code, Cursor or Lovable. Codex shows up as the agent founders add when their first tool hits a limit, costs too much, or after a migration.
How we count: a business is listed only if its own interview says Codex was used to build or run the product. On October 17, 2026 we removed half of the Codex mentions, including sales pitches that "you can build this with ChatGPT Codex," either/or lists, and a writing app that happens to be named Codex Heim.
Contents
Which apps built with Codex make money?
All five are listed here, because the cohort is small enough to show in full.
| Business | What it does | Reported revenue |
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