OpenAI’s new frontier models mark a huge change in how AI will be built

I test-drove both. Here’s what I learned.

[Photos: Getty Images]

In early March, OpenAI unleashed a one-two punch, dropping two major frontier models just days apart.

First, we got the new GPT-5.3, an “instant” model optimized for fast, accurate responses.

Then, OpenAI released GPT-5.4 two days later. This is a “thinking” model optimized for deep analytical work.

I was a beta tester for OpenAI in the early days, and today I spend hundreds of dollars per month using their models through the OpenAI API. 

I’ve tested both GPT-5.3 and 5.4 extensively since their launch. The new models represent a totally different approach, and hint at a major change in how big AI companies build their tech.

OpenAI’s first new model, GPT-5.3, is built for speed. GPT-5.3 generally responds to queries within seconds.

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