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GPT-5.3-Codex

OpenAIProprietaryPending Human Review

GPT-5.3-Codex combines improved coding with GPT-5.2-level professional reasoning for longer tasks involving research, tools, and execution. Released in Codex before API access, it supports steering during work and extends beyond code into data analysis and document creation. Its announcement reports higher speed and more token-efficient engineering than GPT-5.2-Codex.

2026-02-05
Unreleased
Undisclosed proprietary architecture
Proprietary

Specifications

Parameters
Unreleased
Architecture
Undisclosed proprietary architecture
License
Proprietary
Context Window
400,000 tokens
Max Output
128,000 tokens
Training Data Cutoff
Aug 31, 2025
Type
multimodal
Modalities
textimage

Benchmark Scores

Advanced Specifications

Model Family
GPT-5
API Access
Available
Chat Interface
Not Available
Variants
gpt-5.3-codex

Capabilities & Limitations

Capabilities
agentic codingprofessional reasoningvisiontool usecontext compaction
Known Limitations
Can produce incorrect factual claims or code; important results require independent verification.
Notable Use Cases
software lifecycle automationdata analysisdocument creation
Function Calling Support
Yes
Tool Use Support
Yes

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