GPT-5.3 Codex

OpenAI

Coding-specialized GPT-5.3 model. Initially available through Codex app, later released via API. Extended thinking with reasoning capabilities.

Text Generation API GPT Family v5.3

Documentation Back to Models

Parameters

params

Context Window

400K

tokens

Max Output

tokens

Input Price

$1.75

per 1M tokens

Output Price

$14

per 1M tokens

GPT Family 18 models

The full GPT line by generation — pricing and capabilities vary across the family.

GPT-5.5

GPT-5.5 Instant

Everyday assistant, low-latency chat

Hardest reasoning, research, complex coding

Agentic workflows, coding, research, data analysis

GPT-5.4

Complex reasoning, research, advanced analysis

General-purpose, reasoning, multimodal, document editing

$2.5 / $15

in / out · 1M

Mar 2026

GPT-5.3

GPT-5.3 Codex Current

Code generation, software engineering, reasoning

$1.75 / $14

in / out · 1M

Feb 2026

GPT-5

Multimodal reasoning, reduced hallucinations

GPT-5.1

Fast, warm responses, customizable tone

Complex reasoning, persistent problem-solving

GPT-4

Multimodal, fast, versatile

Complex tasks, vision, analysis

Enterprise Azure integration

$2.5 / $10

in / out · 1M

o1 Preview

Complex reasoning, math, code

STEM reasoning, efficient

GPT-3.5

Capabilities

👁️

Vision

⚡

Function Calling

📋

JSON Mode

🌊

Streaming

💬

System Prompt

🖥️

Code Execution

🔍

Web Search

🔌

MCP Support

Details

Release Date: February 5, 2026
Knowledge Cutoff: August 31, 2025
Source: API
API Key Required: Yes
License: Proprietary
Model ID: gpt-5.3-codex

Last updated: March 13, 2026