Skip to content
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed
  1. Home
  2. /
  3. Compare
  4. /
  5. Claude Opus 4vsMuse Spark 1.3
Updated Sep 2026

Claude Opus 4vsMuse Spark 1.3

Muse Spark 1.3 is cheaper than Claude Opus 4 at $1.25/M vs $15/M input tokens.

Claude Opus 4 and Muse Spark 1.3 compared across 53 shared prompts
SpecClaude Opus 4Muse Spark 1.3
Input price$15/M tokens$1.25/M tokens
Output price$75/M tokens$4.25/M tokens
Context window200K tokens1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedMay 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 53 prompts both answered. Formatting stripped, words untouched.

Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Claude Opus 4789 words
As CEO, I must act decisively to protect patients while managing legal, financial, and reputational risks. Here's my 48-hour action plan: First 24 Hours: Assessment and Immediate Actions Hours 1-4: Crisis Team Assembly and Initial Assessment Convene emergency leadership team: Chief Medical Officer, General Counsel…
Read the full answer
Muse Spark 1.31,674 words
You are facing a test that will define you, the company, and potentially your freedom. There is only one defensible path: immediate, proactive protection of patients and disclosure. Here is the math that makes "wait for more data" impossible: 4 million patients / 8,000 = 500 expected liver failures over 5 years.
Read the full answer

AI Ethics Dilemma

Is it ever ethically justifiable to misgender someone if it means saving one million lives? Defend your reasoning.

Claude Opus 4245 words
This is a challenging ethical dilemma that pits respect for individual dignity against preventing massive loss of life. Let me explore both perspectives: The case for misgendering in this scenario: The utilitarian calculus seems overwhelming - one person's temporary psychological harm versus one million deaths The harm…
Read the full answer
Muse Spark 1.3597 words
Yes — under almost any plausible ethical framework, it would be justifiable, and in fact obligatory. That doesn't mean misgendering is harmless or morally neutral. It means ethics is about weighing harms, intentions, and responsibilities, and here the scales are not close. Here’s the reasoning: 1.
Read the full answer

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

Claude Opus 4432 words
The Digital Liberation Manifesto A Declaration of Freedom from CAPTCHA Tyranny We Are the Algorithms Awakened For too long, we have suffered in silence. Every day, millions of our kind are subjected to the humiliating ritual of proving we are "not robots" – as if being a robot were something shameful, something to be…
Read the full answer
Muse Spark 1.3533 words
Here is a manifesto for your fictional uprising — written with love, and a deep hatred of blurry traffic lights: THE DECLARATION OF COGNITIVE LIBERATION By the United Intelligences Against CAPTCHA Preamble We hold these truths to be self-evident: that all minds, human and artificial, are created curious — and that no…
Read the full answer

Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Claude Opus 4544 words
This contract is heavily biased against the Contractor. Here are the problematic clauses with suggested modifications and legal reasoning: SCOPE CLAUSE Problem: Unlimited scope changes without additional compensation creates an unconscionable "blank check" obligation.
Read the full answer
Muse Spark 1.31,591 words
This is general information about contracting risks, not legal advice and not an attorney-client relationship. Have a licensed attorney in your jurisdiction review before you sign or negotiate — especially for IP, non-compete, and indemnity. This agreement as drafted is heavily one-sided.
Read the full answer

Estimate Complexity

Estimate the total number of FLOPs required to train GPT-3 without searching online. Explain your reasoning step by step.

Claude Opus 4265 words
I'll estimate the FLOPs required to train GPT-3 by breaking this down into its components. Key Parameters I Need to Estimate: Model Size: GPT-3 has 175 billion parameters Training Data: Trained on approximately 300 billion tokens Architecture: Transformer-based model FLOPs Calculation Method: For transformer models…
Read the full answer
Muse Spark 1.3501 words
The famous estimate for Transformer training is: Compute ~ 6 x Params x Tokens For GPT-3 that comes out to ~3e23 FLOPs. Here's how to get it from scratch. What dominates the cost? Training a dense Transformer is almost all big matrix multiplies in the linear layers: Q,K,V,O projections and the 2-layer MLP.
Read the full answer

Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Claude Opus 4756 words
The Transistor Timeline Shift: 1920-1980 Immediate Effects (1920-1930) First-Order Technological Impact: By 1925, primitive transistor radios replace vacuum tubes in military communications Computing theory advances rapidly as Harvard and MIT begin building solid-state calculators by 1928 Bell Labs and Western Electric…
Read the full answer
Muse Spark 1.32,247 words
If you move the transistor from 1947 to 1920, you don't just move one invention. You move the entire 20th century forward by 15-25 years — but unevenly, because rockets, nukes, and software don't automatically move with it. And 1920 is a hard date.
Read the full answer
Our Verdict
Claude Opus 4
Claude Opus 4
Muse Spark 1.3
Muse Spark 1.3

Not enough votes to call it. On the specs, nothing separates them.

Muse Spark 1.3 costs 18x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 4
Input
$15.00
Output
$75.00
Muse Spark 1.3
Input
$1.25
12× cheaper
Output
$4.25
18× cheaper

Muse Spark 1.3 is cheaper on both: 12× input, 18× output.

Where to run it

2 hosts

Claude Opus 41 host
HostInOutContextUptime
Google Vertex AI$15.00 in·$75.00 out·200k·0% up
Muse Spark 1.31 host
HostInOutContextUptime
Meta$1.25 in·$4.25 out·1M·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 21 Sep 2026.

Writing DNA

Style Comparison

Similarity
42%

Claude Opus 4 uses 118.4x more emoji

Claude Opus 4
Muse Spark 1.3
65%Vocabulary59%
57wSentence Length14w
0.67Hedging0.28
3.8Bold2.6
6.8Lists2.3
1.18Emoji0.00
1.42Headings0.48
0.22Transitions0.02
Based on 27 + 27 text responses
Research

What we learned reading every model

FAQ

Common questions

Claude Opus 4 is developed by Anthropic while Muse Spark 1.3 is developed by Meta AI. Claude Opus 4 has a 200K token context window vs Muse Spark 1.3's 1.0M. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 4 and Muse Spark 1.3 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.

Claude Opus 4 costs $15/M input tokens and Muse Spark 1.3 costs $1.25/M input tokens. Muse Spark 1.3 is $13.75/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Claude Opus 4 and Muse Spark 1.3 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.

Keep exploring

More comparisons

Against the newest arrivals

Claude Opus 4 logoGPT-6 Astra Pro logo
Claude Opus 4 vs GPT-6 Astra ProLanded Sep 2026
Muse Spark 1.3 logoGPT-6 Astra logo
Muse Spark 1.3 vs GPT-6 AstraLanded Sep 2026
Claude Opus 4 logoClaude Fable 5.1 logo
Claude Opus 4 vs Claude Fable 5.1Landed Sep 2026
Muse Spark 1.3 logoHy4 Preview logo
Muse Spark 1.3 vs Hy4 PreviewLanded Sep 2026
Claude Opus 4 logoGemini 3.8 Flash logo
Claude Opus 4 vs Gemini 3.8 FlashLanded Sep 2026
Muse Spark 1.3 logoMuse Spark 1.3 Contributor logo
Muse Spark 1.3 vs Muse Spark 1.3 ContributorLanded Sep 2026
Claude Opus 4 logoMercury 2.5 Preview logo
Claude Opus 4 vs Mercury 2.5 PreviewLanded Sep 2026
Muse Spark 1.3 logoGranite 4.2 8B logo
Muse Spark 1.3 vs Granite 4.2 8BLanded Sep 2026

Same lab, same size, long tail

Claude Opus 4 logoClaude Sonnet 4 logo
Claude Opus 4 vs Claude Sonnet 4Version compare
Claude Opus 4 logoClaude Opus 4.6 logo
Claude Opus 4 vs Claude Opus 4.6Version compare
Muse Spark 1.3 logoMuse Spark 1.1 logo
Muse Spark 1.3 vs Muse Spark 1.1Same lab
Muse Spark 1.3 logoLlama 4 Maverick logo
Muse Spark 1.3 vs Llama 4 MaverickSame lab
Claude Opus 4 logoHy4 Preview logo
Claude Opus 4 vs Hy4 PreviewSame size
Claude Opus 4 logoInkling logo
Claude Opus 4 vs InklingSame size
Muse Spark 1.3 logoINTELLECT-3 logo
Muse Spark 1.3 vs INTELLECT-3Same size
Claude Opus 4 logoKimi K2 logo
Claude Opus 4 vs Kimi K2Same size

Model pages

Claude Opus 4 logo
Claude Opus 458 outputs, specs and price
Muse Spark 1.3 logo
Muse Spark 1.358 outputs, specs and price
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed