GPT-5.1-Codex vs Claude Opus 4.1

Compare GPT-5.1-Codex by OpenAI against Claude Opus 4.1 by Anthropic, in 6 community votes, claude opus 4.1 wins 100% of head-to-head duels, context windows of 400K vs 200K, tested across 27 shared challenges. Updated February 2026.

In 6 community votes, Claude Opus 4.1 wins 100% of head-to-head duels. Claude Opus 4.1 leads in Reasoning. Based on blind community voting from the RIVAL open dataset of 6+ human preference judgments for this pair.