GPT-5 in the API, especially at "high" reasoning is quite a bit better than o3, especially at web design "style". Also from my own experience, and from some peo

GPT-5 in the API, especially at "high" reasoning is quite a bit better than o3, especially at web design "style". Also from my own experience, and from some people I've talked with it's great at agentic programming and at finding bugs (and then fixing them, of course). ChatGPT 5 in web is a router to lots of different models [1], and the non-reasoning GPT-5 chat model ("gpt-5-chat-latest" in the API) is quite dumb - no significant difference from 4o/4.1. Even if you choose GPT-5 Thinking, there's a chance that your request will be routed to GPT-5 Mini, not to full GPT-5. The only real way to fix that in ChatGPT is to subscribe to Pro and use GPT-5 Pro, but of course that's very expensive. Otherwise people suggest saying "think hard" in the prompt, which might make the router choose the better model. Worse even, Sam Altman publicly said that in the first day of the GPT-5 release their router didn't work properly. [2] I'd suggest trying GPT-5 in API or in apps like Cursor/Windsurf if you want to truly test it. Oh, and from the GPT-5 guide [3] apparently OpenAI considers GPT-5 to be good even at "minimal" reasoning (it's still the full thinking model then, not the chat variant, and will respond much faster): > The minimal setting performs especially well in coding and instruction following scenarios, adhering closely to given directions [1] https://cdn.openai.com/pdf/8124a3ce-ab78-4f06-96eb-49ea29ffb52f/gpt5-system-card-aug7.pdf https://cdn.openai.com/pdf/8124a3ce-ab78-4f06-96eb-49ea29ffb... "Table 1: Model progressions" [2] https://x.com/sama/status/1953893841381273969 https://x.com/sama/status/1953893841381273969 "Yesterday, the autoswitcher broke and was out of commission for a chunk of the day, and the result was GPT-5 seemed way dumber" [3] https://platform.openai.com/docs/guides/latest-model https://platform.openai.com/docs/guides/latest-model