GPT-5.5 is out. It's available in OpenAI Codex and is rolling out to paid ChatGPT subscribers. I've had some preview access and found it to be a fast, effective and highly capable model. As is usually the case these days, it's hard
Simon Willison's WeblogApril 23, 2026
A pelican for GPT-5.5 via the semi-official Codex backdoor API
by Simon Willison's Weblog