One of the best ChatGPT tools is Deep Research, but so far, it has required a subscription. OpenAI now offers a lighter version and expanded it to free users.

Creating a new kind of deep research tool is an attempt from OpenAI to reduce the heavy usage of existing deep research modes it's seeing from users. These kinds of queries can be more expensive for AI providers to execute, due to their process of running more complicated commands and returning more information.

OpenAI is rolling out a 'lightweight' version of its ChatGPT deep research tool, powered by the company's recently launched o4-mini AI model.