GPT-5.1-Codex-Max
GPT-5.1-Codex-Max is a separately released coding model built for sustained software engineering. Native training across multiple context windows through compaction enables project-scale refactors and extended debugging loops. The release also improved token efficiency and Windows work, and added extra-high reasoning effort. Its million-token workflows use repeated compaction rather than a million-token single request.
2025-11-18
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
- Sep 30, 2024
- Type
- multimodal
- Modalities
- textimage
Benchmark Scores
Advanced Specifications
- Model Family
- GPT-5
- API Access
- Not Available
- Chat Interface
- Not Available
- Variants
- gpt-5.1-codex-max
Capabilities & Limitations
- Capabilities
- agentic codingnative context compactionWindows codingcode reviewtool use
- Known Limitations
- Can produce incorrect factual claims or code; important results require independent verification.This API identity was retired on July 23, 2026; preserved for historical coverage.
- Notable Use Cases
- large refactorsmulti-hour coding taskscomplex debugging
- Function Calling Support
- Yes
- Tool Use Support
- Yes