Do Son 
Deep Research is a premium feature developed by OpenAI exclusively for ChatGPT’s paid subscribers, enabling comprehensive web searches and the generation of detailed, professional reports. However, due to the vast volume of data it must process, the operational cost for OpenAI remains exceedingly high.
In an effort to balance operational costs, OpenAI initially established usage quotas for Deep Research across different subscription tiers. Yet, with competitors gradually rolling out similar offerings, OpenAI has now decided to extend access to free-tier users—albeit in the form of a lightweight version.
The lightweight Deep Research tool is powered by OpenAI’s o4-mini model. Although it lacks the full strength and capabilities of the complete Deep Research experience, its significantly lower service costs allow OpenAI to offer users a much higher usage quota.
According to OpenAI, responses generated by the lightweight Deep Research tool will generally be more concise, while still maintaining the depth and quality that users expect. For paying subscribers, the system will default to using the original Deep Research version; should users reach their quota limit, it will automatically switch to the lightweight version to ensure uninterrupted service.
Starting today, the new lightweight Deep Research feature is available to both free users of ChatGPT and subscribers to ChatGPT Plus and ChatGPT Pro. Next week, OpenAI will extend access to ChatGPT Enterprise (Ent) and Education (Edu) subscribers as well.
