GPT-5.4 shipped on March 5. Seven weeks later, on April 23, 2026, OpenAI released GPT-5.5 — and the pace alone tells you something about where this race is headed. This isn't iteration for iteration's sake.
GPT-5.5 is a genuinely different model from the ground up, and if you're building on top of OpenAI's stack, the changes matter in ways that go beyond the benchmark table. Here's everything deve