GPT-5.1-Codex-Max
ModelActiveby OpenAI · family “gpt-codex-max”
GPT-5.1-Codex-Max is OpenAI’s latest agentic coding model, designed for long-running, high-context software development tasks. It is based on an updated version of the 5.1 reasoning stack and trained on agentic... (description from the OpenRouter listing)
in: textin: imageout: textReasoningTool useStructured output
Epoch Capabilities Index
Not scored by Epoch AI
Released
4 Dec 2025
Context window
400K tokens
Max output
128K tokens
Input $ / 1M tokens
$1.25
Output $ / 1M tokens
$10.0
Cached input $ / 1M
$0.13
Each benchmark shown separately with its own source
Benchmark results (3)
| Benchmark | Domain | Score | vs best recorded | Setting | Run | Source |
|---|---|---|---|---|---|---|
| ProofBench | math | 9.0% | 9% | — | — | External ↗ |
| Terminal Bench | agents | 60.4% ±2.7 | 71% | agent: Codex CLI | 19 Nov 2025 | External ↗ |
| METR Time Horizons | agents | 70.8% | 83% | — | — | External ↗ |
Source: Epoch AI Benchmarking Hub (CC BY 4.0). “External” rows are leaderboard results Epoch collects from third parties. Best reported setting per benchmark is shown.
API list price over time
Price history
$ per 1M tokens
11 observations (OpenRouter listing + Internet Archive snapshots). History accumulates with every ingest run; a single point means no change has been observed yet.
Events
- Model launch10mo agoOpenAI releases GPT-5.1-Codex-MaxOpenRouter models API