From googling, there isn’t a free API tier, so is it programmatically using the web interface? Is that against ChatGPT’s terms and likely to get them banned?
I'm not using the Web interface. I'm using the Codex usage everyone, even people with free plan get.
It is how you can connect your Codex account to Pi.dev or OpenCode and it is allowed by OpenAI. One can do this for their Claude Subscription too but Anthropic don't allow it.