GPT-5.1 for developers
GPT-5.1 is available on all paid API tiers with pricing and rate limits the same as GPT-5, plus gpt-5.1-codex and gpt-5.1-codex-mini.
The call on this one
What shipped is free. The call on it, what to do about it and the condition on that, opens with a signup: free, no card, every edition in full.
It becomes $50 a year, and signing up now keeps your first year free.