What is the difference between Claude Sonnet 4 and GPT-5.1 Codex Max?

Claude Sonnet 4 is developed by Anthropic while GPT-5.1 Codex Max is developed by OpenAI. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 4 or GPT-5.1 Codex Max?

It depends on your use case. Claude Sonnet 4 and GPT-5.1 Codex Max each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How can I compare Claude Sonnet 4 and GPT-5.1 Codex Max on Rival?

This page shows a side-by-side comparison of Claude Sonnet 4 and GPT-5.1 Codex Max across shared challenges. You can vote on which model produced the better output in a blind duel. Browsing and voting are free. No account is needed to look; signing in only saves your votes and likes.

Updated Dec 2025

Claude Sonnet 4vsGPT-5.1 Codex Max

GPT-5.1 Codex Max is the newer model, released after Claude Sonnet 4.

Claude Sonnet 4 and GPT-5.1 Codex Max compared across 53 shared prompts
Spec	Claude Sonnet 4	GPT-5.1 Codex Max
Input price	$3/M tokens	—
Output price	$15/M tokens	—
Context window	200K tokens	—
Weights	Closed	Closed
Free API (OpenRouter)	No	No
Released	May 2025	Dec 2025
SWE-bench Verified	72.7%	77.9%