ChatGPT Actions
A ChatGPT action is a developer-facing primitive: a way to extend a custom GPT with a call to an external API. Actions power simple integrations inside custom GPTs; full apps use a deeper integration model. End users mostly don't need to distinguish them, but the difference matters for builders.
What actions are, technically
An action is an OpenAPI-described API call attached to a custom GPT. When you build a GPT in the GPT builder, you can give it one or more actions — each defined by an OpenAPI spec the GPT can call when the user's prompt triggers it. Authentication is OAuth or API key. The GPT decides when to call the action based on the prompt and the action's description. It's a lightweight extension mechanism, not a full integration.
Actions vs apps
Apps are deeper. A ChatGPT app is a partner-vetted integration with its own UI surface inside ChatGPT, persistent connection, richer interaction model, and explicit lifecycle (connect, use, revoke). An action is a single API call hooked into a custom GPT. Apps are products; actions are primitives. Most users never interact with actions directly — they interact with custom GPTs that happen to use them under the hood.
When to use each (for builders)
If you're building for end users and want a polished surface, the apps program is the target — but it requires a partner relationship with OpenAI. If you're building for your own team or a small audience, custom GPTs with actions are vastly easier — anyone with a paid ChatGPT plan can build them, and OAuth-based actions handle most authenticated workflows. Many internal tools that don't justify the app program's overhead live as GPTs with actions.
Why end users see this terminology
Mostly because docs and community posts use 'actions' to describe how a GPT integrates with an API. If you're a user trying to find an integration in chat, you almost certainly want the apps surface, not actions. If you're searching for 'ChatGPT actions' as a developer, you're in the right place.