OpenAI: GPT-5.1-Codex-Max✓ Catalog verified
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 workflows spanning software engineering, mathematics, and research. GPT-5.1-Codex-Max delivers faster performance, improved reasoning, and higher token efficiency across the development lifecycle.
Overview
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 workflows spanning software engineering, mathematics, and research. GPT-5.1-Codex-Max delivers faster performance, improved reasoning, and higher token efficiency across the development lifecycle.
Access: available through the official OpenAI API. Context window: 400K.
Specifications
| API identifier | openai/gpt-5.1-codex-max |
| Provider | OpenAI |
| Model type | Multimodal LLM |
| Context window | 400K catalog |
| Input modalities | text · image |
| Output modalities | text |
| Released | Dec 4, 2025 |
| Tokenizer | GPT |
| Moderated | Yes |
| Architecture modality | text+image->text |
API defaults
{
"top_k": null,
"top_p": null,
"temperature": null,
"presence_penalty": null,
"frequency_penalty": null,
"repetition_penalty": null
}Pricing
Live pricing components for openai/gpt-5.1-codex-max as published in the catalog.
| Pricing component | Raw unit price | Normalized | Unit |
|---|---|---|---|
| Prompt tokens | $0.00000125 | $1.25 / 1M | Per input token |
| Completion tokens | $0.00001 | $10.00 / 1M | Per output token |
| Request fee | N/A | N/A | Per request |
| Image fee | N/A | N/A | Per image unit |
| Web search fee | $0.01 | $0.010000 | Per search request |
Cost calculator
Estimate monthly spend from your own token volumes.
Estimated Total Cost
$2.63Calculated from current list pricing in the ModelsAtlas catalog.Capabilities
| Capability | Status | What it means |
|---|---|---|
| Visual Understanding | ✓ Supported | Image and document analysis support |
| Audio Processing | Not advertised | Speech and voice aligned flows |
| Tool Calling | ✓ Supported | Supports tools / function calling |
| Self-Hosting | Not advertised | Deploy outside managed APIs |
Capability signals
Directional signals derived from model metadata and capability tags — not official benchmark submissions.
Quick start
Call OpenAI: GPT-5.1-Codex-Max through an OpenAI-compatible client.
from openai import OpenAI
client = OpenAI(
base_url="https://openrouter.ai/api/v1",
api_key="YOUR_API_KEY"
)
response = client.chat.completions.create(
model="openai/gpt-5.1-codex-max",
messages=[{"role": "user", "content": "Explain quantum physics."}]
)
print(response.choices[0].message.content)Alternatives
Closest models by context window from a different provider.
| Model | Provider | Context | Input /1M | Actions |
|---|---|---|---|---|
| Meta: Llama 4 Scout | Meta | 328K | $0.08 | View → |
| Amazon: Nova Lite 1.0 | Amazon | 300K | $0.06 | View → |
Head-to-head comparisons
Side-by-side breakdowns of OpenAI: GPT-5.1-Codex-Max against other frontier models.
Sources & attribution
Pricing and metadata are maintained in the ModelsAtlas catalog.
Frequently asked questions
How much does OpenAI: GPT-5.1-Codex-Max cost?
$1.25 per 1M input tokens and $10.00 per 1M output tokens on the official OpenAI API.
What is the context window of OpenAI: GPT-5.1-Codex-Max?
OpenAI: GPT-5.1-Codex-Max supports up to 400K tokens of context.
Does OpenAI: GPT-5.1-Codex-Max support tool / function calling?
Yes, OpenAI: GPT-5.1-Codex-Max supports tool / function calling — you can register tools and the model will emit structured tool calls.
How do I access OpenAI: GPT-5.1-Codex-Max?
Use the official OpenAI API with the model id `openai/gpt-5.1-codex-max`. See the Quick start section above for code examples.