What is the difference between GPT-5.1 Codex Max and Muse Spark 1.3 Contributor?

GPT-5.1 Codex Max is developed by OpenAI while Muse Spark 1.3 Contributor is developed by Meta AI. You can compare their actual outputs across 52 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1 Codex Max or Muse Spark 1.3 Contributor?

It depends on your use case. GPT-5.1 Codex Max and Muse Spark 1.3 Contributor each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 52 challenges so you can judge which fits your needs best.

How can I compare GPT-5.1 Codex Max and Muse Spark 1.3 Contributor on Rival?

This page shows a side-by-side comparison of GPT-5.1 Codex Max and Muse Spark 1.3 Contributor 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 Sep 2026

GPT-5.1 Codex MaxvsMuse Spark 1.3 Contributor

Muse Spark 1.3 Contributor is the newer model, released after GPT-5.1 Codex Max.

GPT-5.1 Codex Max and Muse Spark 1.3 Contributor compared across 52 shared prompts
Spec	GPT-5.1 Codex Max	Muse Spark 1.3 Contributor
Input price	—	$0.1/M tokens
Output price	—	$0.2/M tokens
Context window	—	1.0M tokens
Weights	Closed	Closed
Free API (OpenRouter)	No	No
Released	Dec 2025	Sep 2026