Custom GPT — Definition
A Custom GPT is a configured version of ChatGPT with custom instructions, uploaded knowledge, and optional Actions — designed to be invoked by users on demand, not to run autonomously.
Longer definition
Custom GPTs launched in late 2023 as OpenAI's first structured way to customize ChatGPT for specific use cases. They're individual-scoped (owned by one user, optionally shared), single-turn by default, and invoked by a user message. In 2026, Workspace Agents superseded Custom GPTs for team-scoped automation — but Custom GPTs remain fully supported for single-purpose assistants that don't need autonomous execution.
In practice
If your use case is 'a team member asks it a question, it responds using our knowledge base,' a Custom GPT is the right tool. If your use case is 'every new HubSpot lead gets researched and drafted into an email automatically,' that's a Workspace Agent. Some teams use both.
Common mistakes
- Migrating Custom GPTs that don't need migration — if it works as a single-turn assistant, don't move it
- Confusing Custom GPTs with Workspace Agents in marketing copy — different products with different capabilities
- Expecting Custom GPTs to run on a schedule — they don't; they require user invocation
See also
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