GPT-5.3 Codex High
Parameters
-
Context Length
128K
Modality
Text
Architecture
Dense
License
Proprietary
Release Date
15 Jan 2026
Knowledge Cutoff
-
Technical Specifications
Attention Structure
Multi-Head Attention
Hidden Dimension Size
-
Number of Layers
-
Attention Heads
-
Key-Value Heads
-
Activation Function
-
Normalization
-
Position Embedding
Absolute Position Embedding
GPT-5.3 Codex High
GPT-5.3 Codex High is OpenAI's premier coding model optimized for professional software development. Features state-of-the-art code generation, debugging, and architectural reasoning across 80+ programming languages. Excels at complex refactoring, system design, and understanding large codebases. Trained with enhanced focus on modern development practices, security patterns, and software engineering best practices. Ideal for advanced development workflows, code review, and architectural planning.
About GPT-5.3
OpenAI's GPT-5.3 series represents specialized frontier models with a focus on coding excellence. The Codex variants feature enhanced programming capabilities, deeper understanding of software architecture, and superior performance on coding benchmarks. Designed for professional software development with advanced code generation, debugging, and refactoring abilities.
Other GPT-5.3 Models
- No related models available
Evaluation Benchmarks
Rank
#16
| Benchmark | Score | Rank |
|---|---|---|
Agentic Coding LiveBench Agentic | 0.67 | 🥈 2 |
Coding LiveBench Coding | 0.78 | ⭐ 7 |
Mathematics LiveBench Mathematics | 0.88 | 8 |
Reasoning LiveBench Reasoning | 0.80 | 10 |
Data Analysis LiveBench Data Analysis | 0.63 | 17 |
Rankings
Overall Rank
#16
Coding Rank
#31