---
title: OpenAI: GPT 5.1 Codex API | Text Generation | ModelsLab
description: Advanced coding model with 400K context window, multi-head attention architecture, and dynamic reasoning engine for enterprise software development and.
url: https://modelslab.com/models/openai/openai-gpt-5.1-codex.md
canonical: https://modelslab.com/models/openai/openai-gpt-5.1-codex.md
type: product
component: Playground/LLM/Index
generated_at: 2026-04-15T00:17:20.631676Z
---

OpenAI: GPT-5.1-Codex
---

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

openai-gpt-5.1-codex openai Closed Source Model $5.625000 / call

OpenAI: GPT-5.1-Codex
---

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

Send

### OpenAI: GPT-5.1-Codex

openai openai-gpt-5.1-codex

Copy model ID

PricingInput $1.25 / 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

Related Models
---

Discover similar models you might be interested in

 [View all LLM Models](https://modelslab.com/models?feature=llmaster)

[DR](https://modelslab.com/models/together_ai/deepseek-ai-DeepSeek-R1-0528)[Together AI](https://modelslab.com/models/together_ai)

 [DeepSeek R1 0528

Closed Source Model](https://modelslab.com/models/together_ai/deepseek-ai-DeepSeek-R1-0528)

[DV](https://modelslab.com/models/deepseek/deepseek-ai-DeepSeek-V3)[ModelsLab](https://modelslab.com/models/deepseek)

 [DeepSeek V3-0324

Closed Source Model](https://modelslab.com/models/deepseek/deepseek-ai-DeepSeek-V3)

[ZG](https://modelslab.com/models/open_router/z-ai-glm-5v-turbo)[Open Router](https://modelslab.com/models/open_router)

 [Z.ai: GLM 5V Turbo

Closed Source Model](https://modelslab.com/models/open_router/z-ai-glm-5v-turbo)

[Q2](https://modelslab.com/models/together_ai/Qwen-Qwen2.5-Coder-32B-Instruct)[Together AI](https://modelslab.com/models/together_ai)

 [Qwen 2.5 Coder 32B Instruct

Closed Source Model](https://modelslab.com/models/together_ai/Qwen-Qwen2.5-Coder-32B-Instruct)

[BS](https://modelslab.com/models/open_router/bytedance-seed-seed-1.6-flash)[Open Router](https://modelslab.com/models/open_router)

 [ByteDance Seed: Seed 1.6 Flash

Closed Source Model](https://modelslab.com/models/open_router/bytedance-seed-seed-1.6-flash)

[ML](https://modelslab.com/models/open_router/meta-llama-llama-3.2-3b-instruct-free)[Open Router](https://modelslab.com/models/open_router)

 [Meta: Llama 3.2 3B Instruct (free)

Closed Source Model](https://modelslab.com/models/open_router/meta-llama-llama-3.2-3b-instruct-free)

[IM](https://modelslab.com/models/open_router/inception-mercury-2)[Open Router](https://modelslab.com/models/open_router)

 [Inception: Mercury 2

Closed Source Model](https://modelslab.com/models/open_router/inception-mercury-2)

[![GPT-5](https://images.stablediffusionapi.com/?Image=https://assets.modelslab.ai/generations/a05bf5f0-fe1a-4815-b135-3325beef2516.webp)](https://modelslab.com/models/openai/gpt-5)[Open Ai](https://modelslab.com/models/openai)

 [GPT-5

Closed Source Model](https://modelslab.com/models/openai/gpt-5)

[NN](https://modelslab.com/models/open_router/nvidia-nemotron-nano-12b-v2-vl-free)[Open Router](https://modelslab.com/models/open_router)

 [NVIDIA: Nemotron Nano 12B 2 VL (free)

Closed Source Model](https://modelslab.com/models/open_router/nvidia-nemotron-nano-12b-v2-vl-free)

[GG](https://modelslab.com/models/open_router/google-gemma-3-27b-it-free)[Open Router](https://modelslab.com/models/open_router)

 [Google: Gemma 3 27B (free)

Closed Source Model](https://modelslab.com/models/open_router/google-gemma-3-27b-it-free)

[QQ](https://modelslab.com/models/open_router/qwen-qwen-plus-2025-07-28-thinking)[Open Router](https://modelslab.com/models/open_router)

 [Qwen: Qwen Plus 0728 (thinking)

Closed Source Model](https://modelslab.com/models/open_router/qwen-qwen-plus-2025-07-28-thinking)

[MM](https://modelslab.com/models/together_ai/MiniMaxAI-MiniMax-M2)[Together AI](https://modelslab.com/models/together_ai)

 [MiniMax M2

Closed Source Model](https://modelslab.com/models/together_ai/MiniMaxAI-MiniMax-M2)

[OG](https://modelslab.com/models/open_router/openai-gpt-4-turbo)[Open Router](https://modelslab.com/models/open_router)

 [OpenAI: GPT-4 Turbo

Closed Source Model](https://modelslab.com/models/open_router/openai-gpt-4-turbo)

[QQ](https://modelslab.com/models/open_router/qwen-qwen3-max)[Open Router](https://modelslab.com/models/open_router)

 [Qwen: Qwen3 Max

Closed Source Model](https://modelslab.com/models/open_router/qwen-qwen3-max)

[L3](https://modelslab.com/models/together_ai/meta-llama-Llama-3.2-1B)[Together AI](https://modelslab.com/models/together_ai)

 [Llama 3.2 1B

Closed Source Model](https://modelslab.com/models/together_ai/meta-llama-Llama-3.2-1B)

[QQ](https://modelslab.com/models/alibaba_cloud/qwen-qwen3.5-27b)[Alibaba](https://modelslab.com/models/alibaba_cloud)

 [Qwen: Qwen3.5-27B

Closed Source Model](https://modelslab.com/models/alibaba_cloud/qwen-qwen3.5-27b)

[ML](https://modelslab.com/models/together_ai/meta-llama-Llama-3.3-70B-Instruct-Turbo)[Together AI](https://modelslab.com/models/together_ai)

 [Meta Llama 3.3 70B Instruct Turbo

Closed Source Model](https://modelslab.com/models/together_ai/meta-llama-Llama-3.3-70B-Instruct-Turbo)

[GL](https://modelslab.com/models/open_router/google-lyria-3-clip-preview)[Open Router](https://modelslab.com/models/open_router)

 [Google: Lyria 3 Clip Preview

Closed Source Model](https://modelslab.com/models/open_router/google-lyria-3-clip-preview)

About OpenAI: GPT-5.1-Codex
---

GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....

### Technical Specifications

Model IDopenai-gpt-5.1-codexCategoryLLM ModelsTaskText GenerationPrice$5.625000 per million tokensAddedFebruary 20, 2026

### 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 OpenAI: GPT-5.1-Codex 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": "openai-gpt-5.1-codex",
        "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>
```

View the [full API documentation](https://modelslab.com/models/openai/openai-gpt-5.1-codex/api) for SDKs, code examples in Python, JavaScript, and more.

### Pricing

OpenAI: GPT-5.1-Codex API costs $5.625000 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

[Browse LLM Models](https://modelslab.com/models?feature=llmaster) [More from Openai](https://modelslab.com/models/open_router) [View Pricing](https://modelslab.com/pricing)

OpenAI: GPT-5.1-Codex FAQ
---

### What is OpenAI: GPT-5.1-Codex?

GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks....

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

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

### How much does OpenAI: GPT-5.1-Codex cost?

OpenAI: GPT-5.1-Codex costs $5.625000 per million tokens. ModelsLab uses pay-per-use pricing with no minimum commitments. A free tier is available to get started.

### What is the OpenAI: GPT-5.1-Codex model ID?

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

### Does OpenAI: GPT-5.1-Codex have a free tier?

Yes, ModelsLab offers a free tier that lets you try OpenAI: GPT-5.1-Codex and other AI models. Sign up to get free API credits and start building immediately.

---

*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 - 2026-04-15*