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GPT-5.1-Codex-Max

OpenAIProprietaryPending Human Review

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

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