GPT-5.3-Codex
OpenAI's most capable agentic coding model for complex multi-file development tasks
GPT-5.3-Codex
OpenAI • February 2026
Training Data
Up to December 2025
GPT-5.3-Codex
February 2026
Parameters
~1.7 trillion
Training Method
Code-specialized Unified Architecture
Context Window
400,000 tokens
Knowledge Cutoff
December 2025
Key Features
Agentic Coding • Multi-file Development • Extended Context • Codex Agent
Capabilities
Coding: Maximum
Agentic Tasks: Outstanding
Architecture: Outstanding
What's New in This Version
Most capable agentic coding model, powering the Codex agent for complex development
OpenAI's most capable agentic coding model for complex multi-file development tasks
What's New in This Version
Most capable agentic coding model, powering the Codex agent for complex development
Technical Specifications
Key Features
Capabilities
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