OpenAI's model family, behind ChatGPT and Codex.
GPT is OpenAI's family of large language models. For vibe coders it is the model behind ChatGPT and the Codex coding agent, and it is available in nearly every AI editor.
At a glance — GPT-5.1-Codex-Max
- Cost
- $1.25 in · $10.00 out per 1M tokensMid-range
- Memory
- 400K tokens — about 600 pages
- Reads
- Text · Images
- Can do
- Use tools (agents)
- Structured output
- Thinking mode
- Reliability
- 100.00% uptime, last 24h
- Released
- Dec 4, 2025
Advanced details
- API model ID
openai/gpt-5.1-codex-max- Max output
- 128K tokens
- Max input
- 272K tokens
- Cached input
- $0.125 per 1M
- Tokenizer
- GPT
Providers
The same model, hosted by different companies. OpenRouter picks one per request and falls back to the next if it fails.
| Provider | Input /1M | Output /1M | Cached /1M | Max output | Uptime 24h |
|---|---|---|---|---|---|
| Azure | $1.25 | $10.00 | $0.125 | 128K | 100.00% |
Supported parameters
- include_reasoning
- max_completion_tokens
- reasoning
- reasoning_effort
- response_format
- seed
- structured_outputs
- tool_choice
- tools
Live from OpenRouter, refreshed hourly.
Official apps
Use it in
- Cursor
- Visual Studio Code· via the Codex extension
- GitHub Copilot· in the model picker
- Continue· bring your own key
- Aider· bring your own key
- Devin Desktop· formerly Windsurf
- WebStorm· via JetBrains AI Assistant
- Kilo Code· bring your own key
- OpenCode· bring your own key
- OpenRouter· one API for every model
- OmniRoute· self-hosted gateway
Pairs well with
MCP Servers
Frameworks
Templates
Starter prompts
Copy one, fill in the brackets, and paste it into your tool.
One small, reviewable change · coding
Implement this as the smallest change that fully works: [Describe the feature] Rules: - Reuse what already exists in the codebase before adding anything new - No new dependencies unless you ask first - Add or update one test that fails without your change - Finish with a short summary: files changed, what to check, anything you skipped
Write an AGENTS.md for this repo · context
Read this repository and write an AGENTS.md at its root so Codex and other agents know how to work here. Keep it short and specific: - Setup, test, lint and build commands, exactly as they run - Project layout, and which folders have rules attached - Code style and naming conventions to follow - What to check before calling a task done Only include what is true of this repo. Mark anything you are unsure of with a question.
Reproduce, then fix · debugging
Bug: [what goes wrong, and the exact error] 1. Write a failing test that reproduces it 2. Find the cause, not just the line that throws 3. Fix it at the cause 4. Run that test and the rest of the suite, and show me the output If you cannot reproduce it, stop and tell me what you tried.
Screenshot to component · design
I am attaching a screenshot of [the screen]. Build it as a [React / Next.js] component using this project's existing components and styles. Match layout, spacing and hierarchy, not exact pixels. List anything the screenshot does not show clearly or that you had to guess (hover states, empty states, the mobile layout) and ask me about it rather than inventing it.
Key info
- Pricing
- Freemium
- Category
- Models
Guided walkthroughs
Related reading
- Fundamentals
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