OpenAI: GPT-5.1-Codex-Max
GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic...
Everything else
| Max output | 128K |
|---|---|
| Input / 1M | $1.25 |
| Output / 1M | $10 |
| Cache read / 1M | $0.125 |
| Cache write / 1M | — |
| 1M in + 1M out | $11.25 |
| Takes | text, image |
| Returns | text |
| Tools | yes |
| Reasoning | always on · xhigh, high, medium, low |
| Open weights | no |
| Released | 2025-12-04 |
| Knowledge cutoff | — |
| Retires | — |
| Catalog id | openai/gpt-5.1-codex-max |
Using it
In 00, this model is picked per agent — and per tier, so the model that answers your customers need not be the one that writes your code. Get 00.