gpt-5.1-codex-max· Released Dec 4, 2025

Name: gpt-5.1-codex-max
Brand: 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

From$1.03125/M

Output

From$8.25/M

Context

Up to 400K

Max output

Up to 128K

Modalities

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Input and output show the lowest price across upstreams, for reference. Your actual prices are listed per upstream below.

Upstreams & pricing

Upstream	Context	Max output	Input $/1M	Output $/1M	Cached input $/1M
Zenlayer AI Gateway-openai_compat (Global)From price	400K	128K	$1.03125	$8.25	$0.103125

Routed in real time — you pay the listed price of whichever upstream serves your call.

How to call

curlrequest.sh

curl https://api.tkex.ai/v1/chat/completions \
  -H "Authorization: Bearer $TX_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "model": "openai/gpt-5.1-codex-max",
    "messages": [
      {"role": "user", "content": "Say hello in five words."}
    ]
  }'