Codex is the latest coding agent from OpenAI that runs on a modified o3-model.
Super-coding agent
It can generate several instances of code from your prompts, and even run them in a sandbox to select the best/most efficient version.
OpenAI says it can complete tasks autonomously that would otherwise take hours or days to finish, and they are using it themselves to offload repetitive tasks.
The Plus membership for ChatGPT is $20 a month, and Codex launched as a «research preview» in May for Pro users, who fork out $200 a month.
Update: It appears Codex now also has Internet acccess, which is off by default and comes with a stern warning.
See also: teknotum on the Codex launch, and the announcement thread on X.