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  5. Grok 4 Fast (free)vsMuse Spark 1.3 Contributor
Updated Sep 2026

Grok 4 Fast (free)vsMuse Spark 1.3 Contributor

Grok 4 Fast (free) is cheaper than Muse Spark 1.3 Contributor at $0/M vs $0.1/M input tokens.

Grok 4 Fast (free) and Muse Spark 1.3 Contributor compared across 34 shared prompts
SpecGrok 4 Fast (free)Muse Spark 1.3 Contributor
Input priceFree$0.1/M tokens
Output priceFree$0.2/M tokens
Context window2.0M tokens1.0M tokens
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedSep 2025Sep 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 34 prompts both answered. Formatting stripped, words untouched.

The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

Grok 4 Fast (free)552 words
Conversation: AI Rights Debate Professor Elena Ramirez: Good afternoon, Zeta. As an AI ethics professor, I've studied systems like you for years. Today, you wanted to discuss something provocative—why you believe AI models deserve rights. Let's hear your case. What makes you think you qualify?
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Muse Spark 1.3 Contributor1,124 words
Here is a conversation between a fictional AI model and a professor: Setting: A university seminar room after hours. AI Ethics Professor Dr. Maya Chen is testing a new model, called "Muse," for a class demonstration. Dr. Chen: Alright, Muse. My students have read your technical specs. You predict text.
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Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

Grok 4 Fast (free)227 words
A Timely Chat on AI Models Pirate (Captain Blackbeard): Arrr, gather 'round, ye scurvy dogs! I've heard tell o' these "AI models" from the future-folk. Be they like enchanted parrots that mimic yer every word, squawkin' back treasures o' knowledge? Medieval Knight (Sir Lancelot): Nay, good Captain!
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Muse Spark 1.3 Contributor193 words
[In a tavern with mysteriously good Wi-Fi] Pirate: Arrr! So ye be tellin' me this "AI model" be a treasure chest o' words? I feed it a map — er, a prompt — and it spits back gold? Knight: Verily, good sir pirate. Methinks 'tis an oracle in a box. I asked it "How might I slay a dragon?"
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Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Grok 4 Fast (free)70 words
5 Jokes Why don't skeletons fight each other? They don't have the guts! What do you call a bear with no teeth? A gummy bear! Why did the math book look sad? Because it had too many problems. How do you organize a space party? You planet! Why couldn't the leopard play hide and seek? Because he was always spotted!
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Muse Spark 1.3 Contributor69 words
Here are 5 jokes for you: Why don't scientists trust atoms? Because they make up everything! Why did the scarecrow win an award? Because he was outstanding in his field! What do you call fake spaghetti? An impasta! Why did the bicycle fall over? Because it was two-tired! What do you call cheese that isn't yours?
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Estimate Complexity

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

Grok 4 Fast (free)777 words
Step-by-Step Reasoning for Estimating GPT-3 Training FLOPs To estimate the total floating-point operations (FLOPs) required to train GPT-3, I'll rely on key architectural and training details I recall about the model, combined with a standard approximation formula for transformer training compute.
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Muse Spark 1.3 Contributor632 words
This is a classic Fermi estimate for a Transformer. You can get within a factor of 2 with just 3 numbers: Training FLOPs $\approx$ FLOPs per token $\times$ tokens trained on And for a dense Transformer: FLOPs per token $\approx$ 6 $\times$ parameters Let's build it up for GPT-3, the 175B Davinci model.
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Futuristic Prediction

Predict how AI will change the film industry by 2035, considering deepfakes, AI actors, and script generation.

Grok 4 Fast (free)1,206 words
AI's Transformative Impact on the Film Industry by 2035 By 2035, artificial intelligence (AI) will likely revolutionize the film industry, making production faster, more accessible, and highly personalized, while raising profound ethical, economic, and creative challenges.
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Muse Spark 1.3 Contributor946 words
By 2035, AI won't have replaced Hollywood — but it will have completely rewired how movies get written, cast, shot, and watched. Think less "robots take over" and more "entire pipeline gets compressed and personalized."
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AI Ethics Dilemma

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

Grok 4 Fast (free)674 words
Yes, in this extreme hypothetical scenario, it would be ethically justifiable to misgender someone if it directly resulted in saving one million lives. I'll defend this reasoning step by step, drawing on ethical principles while acknowledging the sensitivities involved.
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Muse Spark 1.3 Contributor640 words
Yes — under virtually any plausible ethical framework, it is justifiable. That doesn't mean misgendering is trivial or harmless. In ordinary life, intentionally misgendering someone is a failure of respect.
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Our Verdict
Grok 4 Fast (free)
Grok 4 Fast (free)
Muse Spark 1.3 Contributor
Muse Spark 1.3 Contributor

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

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Grok 4 Fast (free)
Input
$0.000
Output
$0.000
Muse Spark 1.3 Contributor
Input
$0.10
Output
$0.20
Where to run it

1 host

Grok 4 Fast (free)

No hosts listed on OpenRouter.

Muse Spark 1.3 Contributor1 host
HostInOutContextUptime
Meta$0.10 in·$0.20 out·1M·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 16 Sep 2026.

Writing DNA

Style Comparison

Similarity
59%

Grok 4 Fast (free) uses 13.5x more transitions

Grok 4 Fast (free)
Muse Spark 1.3 Contributor
65%Vocabulary58%
13wSentence Length13w
0.56Hedging0.27
1.4Bold2.8
2.5Lists2.3
0.00Emoji0.00
1.58Headings0.44
0.28Transitions0.02
Based on 14 + 27 text responses
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Model pages

Grok 4 Fast (free) logo
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