GPT-5 Codex API
About
Build advanced reasoning agents with GPT-5 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, native tool calling support. Access GPT-5 Codex via the NanoGPT API with up to 33K output tokens.
Capabilities
Input Modalities
text
Output Modalities
text
Reasoning
Yes
Structured Output
Yes
Tool Use
Yes
WeightsClosed
Temperature
Fixed
Attachment
Not Supported
Limits
Context Window
256K
Tokens
Input Limit
256K
Tokens
Max Output
33K
Tokens
Pricing
Standard (per 1M tokens)
Input
$1.25
Output
$10.00
Caching (per 1M tokens)
Read
$0.13
Frequently Asked Questions
GPT-5 Codex by NanoGPT costs $1.25 per 1M input tokens and $10.00 per 1M output tokens. Cached reads cost $0.13 per 1M tokens.
Model Details
ID
openai/gpt-5-codex
Provider
NanoGPTFamily
gpt-codex
Release Date
Sep 15, 2025
Knowledge Cutoff
Sep 30, 2024
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
NANO_GPT_API_KEY
API Base URL
https://nano-gpt.com/api/v1