What happened
On 23 April 2026 OpenAI released GPT-5.5 — Thinking and Pro for paid tiers — calling it the company's "smartest and most intuitive model"; the models landed in the API the next day (TechCrunch).
The rollout came in stages: on 5 May GPT-5.5 Instant replaced GPT-5.3 Instant as the ChatGPT default for everyone, free tier included (TechCrunch); on 7 May came GPT-5.5-Cyber, a restricted version for vetted cybersecurity teams under the Trusted Access for Cyber program.
Why it matters
GPT-5.5 locked in OpenAI's push toward a "super app": one model behind every product surface. The separate Cyber branch with gated access is the first case of frontier offensive-security capability being carved out into a licensed channel — the industry has started acknowledging models' dual use at the product-line level.
What it means for vibe coding
Every upgrade of ChatGPT's default model raises the baseline: what required a paid plan yesterday is available to everyone today. For tools built on the API, the thing that matters is stable snapshots: OpenAI kept the older models in the API, but the product defaults migrated automatically.