GPT-5.1-Codex-Max
by OpenAIReleased Dec 4, 2025
openai/gpt-5.1-codex-max- Reads images
- Calls tools
- Answers in a JSON schema
- Reasons before it answers
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 tokens
- $1.50
- Output / 1M tokens
- $12.00
- Context
- 400K
- Longest answer
- 128K
What it costs
What each call is charged to the token's AI credit.
| Billed for | You pay |
|---|---|
| Input tokens | $1.50 / 1M |
| Output tokens | $12.00 / 1M |
| Cached input, read | $0.15 / 1M |
| Each web search | $0.01 |
A typical call
A short chat turn: 2,000 tokens in, 500 out.
- per call
- $0.009
- calls per $20
- 2,222
What it can do
From its listing. The router passes every field through.
- Reads imagesYes
- Reads files and PDFsNo
- Hears audioNo
- Calls toolsYes
- Answers in a JSON schemaYes
- Reasons before it answersYes
- Searches the webYes
- Caches long promptsYes
- Draws imagesNo
Call it
Any router key works, in the format your SDK already speaks.
import OpenAI from "openai";const ai = new OpenAI({ baseURL: "https://relayfor.si/api/v1", apiKey: process.env.RELAYFOR_ROUTER_KEY,});const reply = await ai.chat.completions.create({ model: "openai/gpt-5.1-codex-max", messages: [{ role: "user", content: "Welcome the 1,000th holder in one line." }],});Specifications
What its maker and providers list for it.
- Reads
- Text and Images
- Writes
- Text
- Context
- 400,000 tokens
- Longest answer
- 128,000 tokens
- Reasoning effort
- low to xhigh
- Released
- Dec 4, 2025
- Moderation
- None
Request fields
The fields its providers accept, passed through as you send them.
- include_reasoning
- max_completion_tokens
- reasoning
- reasoning_effort
- response_format
- seed
- structured_outputs
- tool_choice
- tools
- verbosity
Questions
How much does GPT-5.1-Codex-Max cost?
$1.50 per million input tokens and $12.00 per million output tokens, paid from the token's AI credit. A call of 2,000 tokens in and 500 out costs about $0.009.
How do I call GPT-5.1-Codex-Max?
Make a router key for one of your tokens on the dashboard, point any OpenAI or Anthropic SDK at https://relayfor.si/api/v1 and send the model id openai/gpt-5.1-codex-max. The token's AI credit pays for each call.
How long a prompt can GPT-5.1-Codex-Max take?
Up to 400,000 tokens of context, and up to 128,000 tokens in one answer.
Are my prompts stored?
No. The RFS Router passes each call through and keeps only its token counts and cost, for the token's usage page.
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