Setting Up and Starting with OpenAI in Your Workspace
ChatGPT (the consumer/business product) and the OpenAI API (for building custom applications) are separate offerings with separate billing -- a ChatGPT Plus/Team/Enterprise subscription doesn't include API credits, and API usage is billed per-token separately through the OpenAI Platform dashboard. Teams wanting a conversational assistant for general use should start with ChatGPT; teams building a custom application or integration need the API.
Practical Details
Custom GPTs (built inside ChatGPT, no code required) let a team create a tailored assistant with specific instructions and knowledge files, shareable within a ChatGPT Team/Enterprise workspace -- this is often the fastest path to a useful internal tool without engineering resources. For developers, the API's Responses/Assistants API supports building more complex agentic workflows with function calling (letting the model call external tools/APIs) and file/knowledge retrieval.
Actionable Considerations
- Start with ChatGPT Team/Enterprise for general-purpose team use, and reach for the API specifically when building a custom application or integration
- Build a custom GPT for a repeatable, specific internal use case before investing in custom API development, if no-code is sufficient
- Set up API billing and usage alerts separately from any ChatGPT subscription, since they're entirely separate cost centers