GPT 5.1 Codex Max

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gpt-5.1-codex-max

OpenAI|Created Dec 5, 2025|400k context

Chat Completions

GPT-5.1-Codex-Max is OpenAI’s newest agentic coding model, created for extended, high-context software development tasks. Built on an enhanced 5.1 reasoning stack, it’s been trained with agentic workflows covering software engineering, mathematics, and research. GPT-5.1-Codex-Max offers faster performance, better reasoning abilities, and increased token efficiency throughout the development process.

Overview Specifications Activity Performance Uptime Examples

Pricing-50%

Pay-as-you-go rates for this model. More details can be found here.

Input Tokens (1M)

$0.63

Cached Input Tokens (1M)

$0.06

Output Tokens (1M)

$5.00

Capabilities

GPT 5.1 Codex Max

Input Tokens (1M)

Cached Input Tokens (1M)

Output Tokens (1M)

GPT 5.1 Codex Max

Input Tokens (1M)

Cached Input Tokens (1M)

Output Tokens (1M)

Input Modalities

Output Modalities