OpenAI: GPT-5.1-Codex-Max

deprecatedproprietary

GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks.

Intelligence
Reasoning
Speed
Context
400K
Max output
128K
Input price
$1.25/1M tokens
Output price
$10/1M tokens

Capabilities

Reasoning & Interaction
Reasoning
Tool Calling
Output Control
Structured Output
JSON Mode
Infrastructure
Streaming

Details

Model IDopenai/gpt-5.1-codex-max
Provider OpenRouter
Creator OpenAI
Familygpt-5.1
Licenseproprietary
Statusdeprecated
Typechat
Input modalitiestext, image
Output modalitiestext
Open weightNo
Parameters—
Architecture—
Context window400K tokens
Max input—
Max output128K tokens
Reasoning tokensYes
Knowledge cutoff
Release date
Deprecation date
Sourceofficial

Tools

Function Callingfunction_calling
Call external functions and APIs

Pricing

Input
$1.25
Output
$10
Cache write
—
Cache read
$0.13
Batch in
—
Batch out
—

Family Comparison: gpt-5.1

ModelContextMax outPricing
OpenAI: GPT-5.1-Codex-Mini400K128K$0.25$2
OpenAI: GPT-5.1 (batch)400K128K$0.63$5
OpenAI: GPT-5.1 Chat128K32K$1.25$10
OpenAI: GPT-5.1-Codex-Max400K128K$1.25$10
OpenAI: GPT-5.1-Codex400K128K$1.25$10
OpenAI: GPT-5.1400K128K$1.25$10

API

GET/v1/models/openrouter/openai/gpt-5.1-codex-max