Happy Horse 1.0 is now on ModelsLab

Try Now
Skip to main content
Available now on ModelsLab · Language Model

OpenAI: GPT-5.1-Codex-MaxCode Autonomously for Hours

Try OpenAI: GPT-5.1-Codex-MaxAPI Documentation

Master Long-Running Tasks

Context Compaction

Million-Token Workflows

Handles multiple context windows via native compaction for coherent tasks over millions of tokens.

xHigh Reasoning

77.9% SWE-Bench Score

Achieves top code quality on complex problems with 30% fewer thinking tokens than predecessors.

Extended Execution

24-Hour Autonomy

Runs continuously, iterating code, fixing tests, and checkpointing progress without intervention.

Examples

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

Copy any prompt below and try it yourself in the playground.

Full Stack App

“Plan, implement, and test a complete React frontend with Node.js backend for a task management app, handling authentication, database integration, and API endpoints across multiple files.”

Code Refactor

“Analyze existing 500k-token Python codebase, identify inefficiencies, refactor for performance, add unit tests, and verify against benchmarks autonomously.”

Agent Loop

“Build self-improving agent that generates, debugs, and deploys ML model training pipeline, iterating until accuracy exceeds 95% on dataset.”

Multi-File Project

“Develop enterprise-grade TypeScript library for data processing, including docs, examples, CI/CD setup, and integration tests over extended session.”

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 
import requests


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

FAQ

Common questions about OpenAI: GPT-5.1-Codex-Max

Read the docs

OpenAI: GPT-5.1-Codex-Max is an agentic coding model for long-running software tasks. It uses context compaction for million-token contexts. Access via LLM endpoints.

It compacts contexts natively to work coherently over millions of tokens. Supports 24+ hour autonomous execution with progress checkpoints. Ideal for refactors and multi-file projects.

xhigh effort level scores 77.9% on SWE-bench Verified. Uses 30% fewer tokens for deeper analysis on complex coding. Configurable via reasoning.effort parameter.

Yes, it's a specialized update for agentic coding with improved time horizons and benchmarks. Outperforms on software engineering tasks like PRs and reviews.

Excels in planning, implementing, testing features autonomously. Handles frontend coding, Q&A, math, and research via agentic training. 400k context window.

Use v1/chat/completions or v1/responses endpoints. Bring your key for GitHub Copilot or direct API calls. Enable in model picker for Pro plans.

Ready to create?

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

Try OpenAI: GPT-5.1-Codex-MaxAPI Documentation