More than 4,000 listings, and four in ten of them chase the same two categories. What the early Facebook platform says about where the real opening is inside ChatGPT and Claude.
ChatGPT opened its app directory to outside developers in December 2025 (OpenAI, 17 December 2025). Nine months later it held more than 4,000 listings from more than 3,600 companies, according to a live count by BigIdeasDB on 19 September 2026.
The interesting number is where those listings sit. Productivity and business operations account for 989 and 791 of them: 41.9% of the directory in two categories. At the other end, healthcare has 77, communication 38 and security 35.
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That shape is familiar. It is what a new platform looks like before anyone knows what it is for.
Facebook opened its platform to outside developers in May 2007. Zynga, founded the month before, shipped its first Facebook game that July. FarmVille launched in June 2009 and passed 11 million daily players within nine weeks. Zynga's revenue went from $19.4 million in 2008 to $597.5 million in 2010, almost all of it through Facebook, and by 2011 it was about 12% of Facebook's own revenue (Zynga S-1, July 2011; Facebook S-1, February 2012).
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Most of the apps built in Facebook's first two years are forgotten.
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The same: the audience is already there. OpenAI said in February 2026 that ChatGPT had about 900 million weekly users. A listing puts your product inside a habit people already have, instead of asking them to form a new one.
Different: ranking now follows use. Anthropic's Connectors Directory, which serves Claude on the web, desktop, mobile and in Claude Code from one catalogue, ranks listings on usage and can suggest a connector in the middle of a conversation when it fits the task (Anthropic documentation, checked 31 October 2026). A listing nobody uses twice sinks, however early it arrived.
[[take]]
For most businesses this is a few weeks of a developer's time and no media spend. The two plays below have the steps, the cost to test and when to stop.
Sources: OpenAI, Developers can now submit apps to ChatGPT (17 December 2025). BigIdeasDB, ChatGPT Apps Directory: A Market Map for Builders, figures queried 19 September 2026. Anthropic, Connectors Directory documentation (checked 31 October 2026). OpenAI weekly users as reported in February 2026. Zynga S-1 (1 July 2011). Facebook S-1 (February 2012). Checked 2 November 2026.