GPT 5.1 Codex API
About
Build advanced reasoning agents with GPT 5.1 Codex, a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers cost-effective pricing at $1.25/1M input and $10.00/1M output tokens. Access GPT 5.1 Codex via the NanoGPT API with up to 128K output tokens.
Capabilities
Input Modalities
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Output Modalities
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Reasoning
Yes
Structured Output
No
Tool Use
No
WeightsClosed
Temperature
Fixed
Attachment
Supported
Limits
Context Window
400K
Tokens
Input Limit
400K
Tokens
Max Output
128K
Tokens
Pricing
Standard (per 1M tokens)
Input
$1.25
Output
$10.00
Frequently Asked Questions
GPT 5.1 Codex by NanoGPT costs $1.25 per 1M input tokens and $10.00 per 1M output tokens.
Model Details
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
NANO_GPT_API_KEY
API Base URL
https://nano-gpt.com/api/v1