GPT-5 is an OpenAI model family released on 7 August 2025 that routes each question to either a fast model or a deeper reasoning model.
In plain words
GPT-5 decides for you how much to think. A router looks at the conversation, how hard the task is and whether tools are needed, then sends it to a quick model or a thinking model. OpenAI said it hallucinated less and was its strongest coding model at launch. It has since been followed by newer versions; the API now points to GPT-6 Astra as the top model.
A quick example
Ask a simple fact and the fast model answers at once. Ask it to 'think hard' about a tricky proof and the router hands the question to the reasoning model, which takes longer before replying.
Where you'll meet it
- ChatGPT, for all users from launch.
- Multi-step tasks that use several tools.
Related
Sources
- DocsIntroducing GPT-5, OpenAI · read 29 Sept 2026
- DocsModels, OpenAI API docs · read 26 Oct 2026
Checked by WhatIsAI against the sources above · 26 Oct 2026. Spotted an error? Report it.