OpenAI

GPT-5.1-Codex-Max

openai/gpt-5.1-codex-max

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Specification

Published by the vendor; the platform bills at the target's declared price.

GPT-5.1-Codex-Max

reasoning tools

OpenAI openai/gpt-5.1-codex-max

GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic...

Input $/1M: $1.25
Output $/1M: $10.0
Context: 400K
Max output: 128K
Released: Dec 4, 2025
Modalities: textimage

Cached input reads $0.13 per 1M

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targets.yamlyaml

# targets.yaml - declare a target that runs GPT-5.1-Codex-Max
targets:
  - id: gpt-5-1-codex-max
    kind: llm
    name: GPT-5.1-Codex-Max
    metadata:
      model: openai/gpt-5.1-codex-max          # links the target to this catalogue entry
    capabilities:
      domains: [general]
      supports_tools: true
      context_window: 400000
    cost:
      usd_per_1k_tokens: 0.005625

Price among OpenAI models

Input list price per million tokens; GPT-5.1-Codex-Max is the 7th cheapest of 13 listed.

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