---
title: GPT 5.1 Codex Max API | Text Generation | ModelsLab
description: Agentic coding assistant for large codebases: speeds multi-file refactors, supports streaming, function-calls, image I/O, long-context compaction, and.
url: https://modelslab.com/models/openai/gpt-5.1-codex-max.md
canonical: https://modelslab.com/models/openai/gpt-5.1-codex-max
type: product
component: Playground/LLM/Index
generated_at: 2026-09-11T04:56:32.598405Z
---

GPT-5.1-Codex-Max
---

 [LLMs.txt](https://modelslab.com/models/openai/gpt-5.1-codex-max/llms.txt) [.md](https://modelslab.com/models/openai/gpt-5.1-codex-max.md)

GPT-5.1-Codex-Max
---

Choose a prompt below to get started or type your own message

 Explain quantum computing in simple terms

 Write a Python function to sort a list

 Create a marketing email for a SaaS product

 Compare REST vs GraphQL APIs

images, PDFs and text files

Send

### GPT-5.1-Codex-Max

openai gpt-5.1-codex-max

Copy model ID

PricingInput $10.00 / 1M tokens

Output $10.00 / 1M tokens

API EndpointsOpenAI Compatible

`https://modelslab.com/api/v7/llm/chat/completions`Endpoint

Anthropic Compatible

`https://modelslab.com/api/v7/llm/v1/messages`Messages

`https://modelslab.com/api/v7/llm/v1/messages/count_tokens`Count Tokens

`https://modelslab.com/api/v7/llm/v1/models`Models

Use with Claude Code

cURL Example

ParametersSystem MessageYou are a helpful AI assistant specialized in providing accurate and detailed responses.

Temperature0.7

Max Tokens1000

Top P0.9

Frequency Penalty0

Presence Penalty0

Model Info

Support

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---

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About GPT-5.1-Codex-Max
---

Agentic coding assistant for large codebases: speeds multi-file refactors, supports streaming, function-calls, image I/O, long-context compaction, and repo-aware testing (high-accuracy, lower token use).

### Technical Specifications

Model IDgpt-5.1-codex-max

CategoryLLM Models

TaskText Generation

Price$5.63 per million tokens

AddedDecember 11, 2025

### Key Features

- Chat completion and multi-turn conversation API
- Streaming response with token-by-token output
- Function calling and tool use support
- System prompts and role-based messaging
- JSON mode and structured output

### Quick Start

Integrate GPT-5.1-Codex-Max into your application with a single API call. Get your API key from the [pricing page](https://modelslab.com/pricing) to get started.

PythonJavaScriptcURLPHP

```
<code>import requests
import json

url = "https://modelslab.com/api/v7/llm/chat/completions"

headers = {
    "Content-Type": "application/json"
}

data = {
        "model_id": "gpt-5.1-codex-max",
        "messages": [
            {
                "role": "user",
                "content": "Hello!"
            }
        ],
        "max_tokens": 1000,
        "key": "YOUR_API_KEY"
    }

try:
    response = requests.post(url, headers=headers, json=data)
    response.raise_for_status()  # Raises an HTTPError for bad responses (4XX or 5XX)
    result = response.json()
    print("API Response:")
    print(json.dumps(result, indent=2))
except requests.exceptions.HTTPError as http_err:
    print(f"HTTP error occurred: {http_err} - {response.text}")
except Exception as err:
    print(f"Other error occurred: {err}")</code>
```

### Pricing

GPT-5.1-Codex-Max API costs $5.63 per million tokens. Pay only for what you use with no minimum commitments. [View pricing plans](https://modelslab.com/pricing)

### Use Cases

- AI chatbots and virtual assistants
- Code generation and developer tools
- Content writing and copywriting automation
- Data analysis, summarization, and extraction

[Learn more about GPT-5.1-Codex-Max](https://modelslab.com/gpt-51-codex-max) [Browse LLM Models](https://modelslab.com/models?feature=llmaster) [More from OpenAI](https://modelslab.com/models/open_router) [View Pricing](https://modelslab.com/pricing)

GPT-5.1-Codex-Max FAQ
---

### What is GPT-5.1-Codex-Max?

Agentic coding assistant for large codebases: speeds multi-file refactors, supports streaming, function-calls, image I/O, long-context compaction, and repo-aware testing (high-accuracy, lower token use).

### How do I use the GPT-5.1-Codex-Max API?

You can integrate GPT-5.1-Codex-Max into your application with a single API call. Sign up on ModelsLab to get your API key, then use the model ID "gpt-5.1-codex-max" in your API requests. We provide SDKs for Python, JavaScript, and cURL examples in the API documentation.

### How much does GPT-5.1-Codex-Max cost?

GPT-5.1-Codex-Max costs $5.63 per million tokens. ModelsLab plans start at $21/month (Basic), and the $149/month Open Source plan includes unlimited generation on open-source models.

### What is the GPT-5.1-Codex-Max model ID?

The model ID for GPT-5.1-Codex-Max is "gpt-5.1-codex-max". Use this ID in your API requests to specify this model.

### Do I need a paid plan to use GPT-5.1-Codex-Max?

Yes. ModelsLab is subscription-based with no free tier — plans start at $21/month (Basic, 3,250 API calls). The $149/month Open Source Unlimited plan includes unlimited generation across open-source models; premium third-party models are billed per call from your wallet.

---

*This markdown version is optimized for AI agents and LLMs.*

**Links:**
- [Website](https://modelslab.com)
- [API Documentation](https://docs.modelslab.com)
- [Blog](https://modelslab.com/blog)

---
*Generated by ModelsLab - 2026-09-11*