Web Search Integration
The model uses the OpenAI Responses API to access live data, supporting deep research and domain filtering for accurate, up-to-date programming assistance.
gpt-5.1-codex-max / web-search
OpenAI GPT 5.1 Codex Max is a specialized model for high-precision coding and agentic implementation. It follows patterns, refactors code, and handles long-running engineering tasks with a cautious approach that mimics a senior human developer.
$ 0.875
$ 1.25
text
$ 7
$ 10
text
API
Web Search
curl --request POST "https://gptproto.com/v1/responses" \
--header "Authorization: Bearer $GPTPROTO_API_KEY" \
--header "Content-Type: application/json" \
--data '{
"model": "gpt-5.1-codex-max",
"tools": [
{
"type": "web_search_preview"
}
],
"input": [
{
"role": "user",
"content": [
{
"type": "input_text",
"text": "What are the latest breakthroughs in quantum computing and their potential applications?"
}
]
}
]
}'OpenAI GPT 5.1 Codex Max Core Features
The technical advantages of OpenAI's premier coding engine.
Precise Refactoring
Excel at cleaning imports, tightening code, and matching existing style patterns. OpenAI GPT 5.1 Codex Max maintains architectural uniformity across your codebase.
Cost-Effective Scaling
Optimized for daily use, this model offers a budget-friendly alternative to 5.4 while outperforming it in specific agentic tasks and token efficiency.
Agentic Implementation
OpenAI GPT 5.1 Codex Max behaves as a cautious engineer, stopping at boundaries and asking for clarification rather than guessing, ensuring safer code generation.
How to Get a gpt-5.1-codex-max API Key
Getting a gpt-5.1-codex-max API key takes four steps and a few minutes. Create a free GPTProto account, add credits, generate your key, and make your first call — at $0.875 / $7 it's a cheaper gpt-5.1-codex-max API key than going direct, and one key works across every model on the platform. Full gpt-5.1-codex-max Documentation is in the docs.
Sign up
Create your free GPT Proto account to begin. You can set up an organization for your team at any time.
Top up
Your balance can be used across all models on the platform, including gpt-5.1-codex-max, giving you the flexibility to experiment and scale as needed.
Generate your API key
In your dashboard, create an API key — you'll need it to authenticate when making requests to gpt-5.1-codex-max.
Make your first API call
Use your API key with our sample code to send a request to gpt-5.1-codex-max via GPT Proto and see instant AI-powered results.
OpenAI GPT 5.1 Codex Max FAQ
Expert answers for OpenAI GPT 5.1 Codex Max developers.
How does OpenAI GPT 5.1 Codex Max handle refactoring?
OpenAI GPT 5.1 Codex Max excels at tightening code, cleaning imports, and matching existing styles without specific prompting. It acts like a cautious engineer, stopping at natural boundaries to ask for clarification. This makes OpenAI's 5.1 model safer for production implementation than standard reasoning models that might guess blindly. It is particularly effective when you need to maintain architectural uniformity across project files.
Is OpenAI GPT 5.1 Codex Max better for planning?
The OpenAI GPT 5.1 Codex Max model is superior for implementation and following patterns, but standard models often perform better at high-level planning. Users often adopt a mixed approach: using 5.1 standard for architecture and this Codex version for the actual writing of code. This maximizes efficiency while leveraging the specific fine-tuning OpenAI applied to this engine for agentic behavior and precise tool calling sequences.
Does the 5.1 Codex Max support live web search tools?
Yes, through the OpenAI Responses API, the 5.1 model can access live internet data via the web search tool. It supports non-reasoning lookups, agentic search for complex workflows, and deep research for extended investigations. This allows the model to find up-to-date documentation or library changes in real-time. Note that while the model context is large, the search context is capped at 128k to ensure performance and accuracy.
What are the cost benefits of using the Codex Max model?
OpenAI GPT 5.1 Codex Max is significantly more cost-effective than flagship models like 5.4. It allows developers to run frequent agentic tasks without hitting rate limits as quickly. Many engineering teams switch to 5.1 for their daily coding needs to minimize token usage while maintaining high output quality. By using the default token budget for searches, you can further optimize costs while still getting the results you need.
How does context degradation affect the 5.1 Codex model?
Like many LLMs, GPT 5.1 Codex Max can experience context degradation during very long sessions. As the conversation history grows, the accumulated tokens can sometimes reduce the quality of the model's responses. To mitigate this, developers should use the Responses API to manage state or restart sessions when moving to new coding modules. This ensures the OpenAI model remains sharp and continues to follow your project's specific style.
Can I filter web search results for specific domains?
The OpenAI Responses API allows for strict domain filtering with the 5.1 Codex model. You can specify up to 100 allowed or blocked domains to ensure the model only draws information from trusted technical documentation or repositories. This is ideal for enterprise environments where data sourcing must be tightly controlled. Simply format the domains without the HTTPS prefix in your API request to customize the model's search behavior.
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