It was available in the API from Feb 2025 to July 2025, I believe. There's probably another world where we could have kept it around longer, but there's a surprising amount of fixed cost in maintaining / optimizing / serving models, so we made the call to focus our resources on accelerating the next gen instead. A bit of a bummer, as it had some unique qualities.
Just wondering: Why was it never made available via API? You can just charge whatever per token to make sure it's profitable like o1-pro.
I use it via my ChatGPT-Pro subscription, but I still find the API omission weird.