---
title: GPT-5.1-Codex-Max — Agentic Coding LLM | ModelsLab
description: Access GPT-5.1-Codex-Max API for agentic coding with 400K context and multi-window compaction. Generate secure apps and refactor projects now.
url: https://modelslab.com/gpt-51-codex-max
canonical: https://modelslab.com/gpt-51-codex-max
type: website
component: Seo/ModelPage
generated_at: 2026-04-24T23:29:27.112432Z
---

Available now on ModelsLab · Language Model

GPT-5.1-Codex-Max
GPT-5.1-Codex-Max Codes Autonomously
---

[Try GPT-5.1-Codex-Max](/models/openai/gpt-5.1-codex-max) [API Documentation](https://docs.modelslab.com)

![GPT-5.1-Codex-Max](https://assets.modelslab.ai/generations/3d49b0e2-89a1-409b-ae7b-16ca83a2870e.png)

Master Agentic Coding Workflows
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Multi-Context Windows

### Handle 400K Tokens Seamlessly

Process entire codebases with native compaction for sustained sessions.

Agentic Reasoning

### Debug and Refactor Projects

Autonomously fix tests, write units, and resolve dependencies across files.

Security Built-In

### Detect Vulnerabilities Early

Scan for insecure patterns like hard-coded credentials in full audits.

Examples

See what GPT-5.1-Codex-Max can create
---

Copy any prompt below and try it yourself in the [playground](/models/openai/gpt-5.1-codex-max).

REST API Scaffold

“Generate a secure Node.js REST API for user authentication with JWT, including database schema, routes, middleware for input validation, unit tests, and error handling. Use TypeScript and follow OWASP best practices.”

Microservice Refactor

“Refactor this provided Express.js microservice codebase: optimize database queries, add caching with Redis, implement rate limiting, fix cross-file dependencies, and generate updated Docker configuration.”

CLI Tool Build

“Create a Python CLI tool for log analysis: parse JSON logs, detect anomalies using statistical methods, output visualizations with Matplotlib, include setup script and comprehensive tests.”

Frontend Component

“Build a React component library for data dashboards: include responsive charts with Recharts, state management via Zustand, TypeScript types, Storybook stories, and accessibility features.”

For Developers

A few lines of code.
Agentic code. One call.
---

ModelsLab handles the infrastructure: fast inference, auto-scaling, and a developer-friendly API. No GPU management needed.

- **Serverless:** scales to zero, scales to millions
- **Pay per token,** no minimums
- **Python and JavaScript SDKs,** plus REST API

[API Documentation ](https://docs.modelslab.com)

PythonJavaScriptcURL

Copy

```
<code>import requests

response = requests.post(
    "https://modelslab.com/api/v7/llm/chat/completions",
    json={
  "key": "YOUR_API_KEY",
  "prompt": "",
  "model_id": ""
}
)
print(response.json())</code>
```

FAQ

Common questions about GPT-5.1-Codex-Max
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[Read the docs ](https://docs.modelslab.com)

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

GPT-5.1-Codex-Max API provides access to OpenAI's agentic coding model for software tasks. It supports 400K token contexts via compaction. Ideal for autonomous debugging and generation.

### How does gpt 5.1 codex max model differ from GPT-4?

Gpt 5.1 codex max model uses multi-context windows and agentic loops unlike GPT-4's 8K limit. It automates project refactors and security checks. Benchmarks show 77.9% on SWE-Bench.

### Is GPT-5.1-Codex-Max alternative to Copilot available?

GPT-5.1-Codex-Max model serves as a direct alternative via API for IDEs and CLI. Enable in VS Code or GitHub Copilot with keys. Supports long-horizon engineering workflows.

### What context length supports gpt-5.1-codex-max api?

Gpt-5.1-codex-max api handles 400K tokens with parallel multi-windows. Compaction retains state across sessions. Fits large microservices without manual slicing.

### Can GPT-5.1-Codex-Max LLM perform security audits?

GPT-5.1-Codex-Max LLM scans codebases for vulnerabilities like missing validation. It flags hard-coded secrets during analysis. Built-in filters enhance detection accuracy.

### How to integrate gpt 5.1 codex max api in code?

Use standard LLM endpoint calls with your API key. Specify model as GPT-5.1-Codex-Max for agentic tasks. Handles iterative refinement in single sessions.

Ready to create?
---

Start generating with GPT-5.1-Codex-Max on ModelsLab.

[Try GPT-5.1-Codex-Max](/models/openai/gpt-5.1-codex-max) [API Documentation](https://docs.modelslab.com)

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*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)

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*Generated by ModelsLab - 2026-04-25*