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GPT-5.1-Codex-Max

gpt-5.1-codex-max

GPT-5.1 Codex Max is OpenAI's advanced agentic coding model, built for long-running, high-context development work. Using an upgraded 5.1 reasoning stack and training on real engineering workflows, it delivers faster performance, stronger reasoning, and better token efficiency across the full software lifecycle.

Context
400K tokens
Endpoint

Service Status

Status information temporarily unavailable

Apertis cannot confirm the current service state. This is not a report that the model is down.

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Pricing

Input$0.375 / 1M
Output$3.00 / 1M
Cache Write (5m)$0.375 / 1M
Cache Write (1h)$0.375 / 1M
Cache Read$0.375 / 1M
Web Search$0 / 1M

Quick Start

Select an endpoint and copy a working example for this model.

Endpoint
python
from openai import OpenAI client = OpenAI(    api_key="YOUR_API_KEY",    base_url="https://api.apertis.ai/v1") response = client.chat.completions.create(    model="gpt-5.1-codex-max",    messages=[        {"role": "user", "content": "Hello!"}    ],    max_tokens=1024,    temperature=0.7) print(response.choices[0].message.content) # Optional: Enable context compression to reduce token usage# response = client.chat.completions.create(#     model="gpt-5.1-codex-max",#     messages=[{"role": "user", "content": "Hello!"}],#     extra_body={"compression": {"enabled": True, "model": "gpt-4.1-mini"}}# )

Supported Parameters

API docs
Common7 params
modelmessagesmax_tokenstemperaturetop_pstreamtools
Extended4 params
reasoning_effortstream_optionsthinkingextra_body

Cursor IDE Model IDs

Use these namespaced identifiers in Cursor IDE to avoid conflicts with built-in models.

gpt-5.1-codex-max

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