OpenAI
Codex-oriented GPT-5.1 variant for agentic software engineering, repository edits, and tool-augmented coding tasks.
50.4
Quality Score
1235
Arena ELO
Undisclosed
Parameters
200K
Context
Use this section to answer one simple question first: how much outside evidence do we have that this model performs well? Structured benchmark scores appear first, then official provider evidence, then live arena signal.
This model has normalized benchmark rows, so scores here are directly comparable across benchmark sources.
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Nov 2025
Released
These are recent benchmark or leaderboard claims from official provider sources. They are useful for freshness and context, but they are not treated the same as normalized independent benchmark rows.
gpt-5.1-codex - SWE-Bench Verified
SWE-Bench Verified resolved rate 66.0
View sourceIntroducing GPT‑5 for developers
Introducing GPT‑5 for developers | OpenAI Skip to main content Research Products Business Developers Company Foundation (opens in a new window) Log in Try ChatGPT (opens in a new window) Research Products Business Developers Company Foundation (opens in a new window) Try ChatGPT (opens in a new window) Login OpenAI Table of contents Introduction New features Safety Availability & pricing Detailed benchmarks August 7, 2025 Product Introducing GPT‑5 for developers The best
View source1235
ELO Score
1227 - 1243
95% Confidence
+/-8 points
10.4K
Battles
Mar 27, 2026
Last Updated