GPT-5.3-Codex
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