GPT-5.1-Codex
ModelActiveby OpenAI · family “gpt-codex”
GPT-5.1-Codex is a specialized version of GPT-5.1 optimized for software engineering and coding workflows. It is designed for both interactive development sessions and long, independent execution of complex engineering tasks.... (description from the OpenRouter listing)
in: textin: imageout: textReasoningTool useStructured output
Epoch Capabilities Index
Not scored by Epoch AI
Released
13 Nov 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 (1)
| Benchmark | Domain | Score | vs best recorded | Setting | Run | Source |
|---|---|---|---|---|---|---|
| Terminal Bench | agents | 57.8% ±2.9 | 68% | agent: Codex CLI | 16 Nov 2025 | 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 recorded prices on 6 Dec 2025 (OpenRouter listing + Internet Archive snapshots); re-read on every data refresh, most recently 2h ago. Steps show when the price changed.
Events
- Model launchMajorOpenAI releases GPT-5.1-CodexOpenRouter models API