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AI/ML API

GPT-5.3 Codex API

AI/ML API
About

Build advanced reasoning agents with GPT-5.3 Codex, a specialized AI model optimized for complex logic and chain-of-thought tasks. This model delivers cost-effective pricing at $4.81/1M input and $38.51/1M output tokens, native tool calling support. Access GPT-5.3 Codex via the AI/ML API API with up to 128K output tokens.

Capabilities

Input Modalities

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Output Modalities

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Reasoning
Yes
Structured Output
Yes
Tool Use
Yes
WeightsClosed
Temperature
Adjustable
Attachment
Supported
Limits
Context Window
400K

Tokens

Input Limit
272K

Tokens

Max Output
128K

Tokens

Pricing

Standard (per 1M tokens)

Input
$4.81
Output
$38.51

Caching (per 1M tokens)

Read
$0.48
Frequently Asked Questions

GPT-5.3 Codex by AI/ML API costs $4.81 per 1M input tokens and $38.51 per 1M output tokens. Cached reads cost $0.48 per 1M tokens.

Model Details
ID
openai/gpt-5.3-codex
Provider
AI/ML API
Family
gpt-codex
Release Date
Feb 5, 2026
Knowledge Cutoff
Aug 31, 2025
API Integration
NPM Package
@ai-sdk/openai-compatible
Environment Variables
AIMLAPI_API_KEY
API Base URL
https://api.aimlapi.com/v1
Documentation