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

GPT-5.1-Codex is developed by OpenAI while Muse Spark 1.3 Contributor is developed by Meta AI. GPT-5.1-Codex has a 400K token context window vs Muse Spark 1.3 Contributor's 1.0M. 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 or Muse Spark 1.3 Contributor?

It depends on your use case. GPT-5.1-Codex 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 much does GPT-5.1-Codex cost compared to Muse Spark 1.3 Contributor?

GPT-5.1-Codex costs $1.25/M input tokens and Muse Spark 1.3 Contributor costs $0.1/M input tokens. Muse Spark 1.3 Contributor is $1.15/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

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

This page shows a side-by-side comparison of GPT-5.1-Codex 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-CodexvsMuse Spark 1.3 Contributor

Muse Spark 1.3 Contributor is cheaper than GPT-5.1-Codex at $0.1/M vs $1.25/M input tokens.

GPT-5.1-Codex and Muse Spark 1.3 Contributor compared across 52 shared prompts
Spec	GPT-5.1-Codex	Muse Spark 1.3 Contributor
Input price	$1.25/M tokens	$0.1/M tokens
Output price	$10/M tokens	$0.2/M tokens
Context window	400K tokens	1.0M tokens
Weights	Closed	Closed
Free API (OpenRouter)	No	No
Released	Nov 2025	Sep 2026