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  1. Home/
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  3. Claude Sonnet 5 vs Grok 4 Fast (free)
Updated Jun 2026

Claude Sonnet 5 vs Grok 4 Fast (free)

Grok 4 Fast (free) is cheaper than Claude Sonnet 5 at $0/M vs $2/M input tokens.

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
Claude Sonnet 5
Loading the build
Grok 4 Fast (free)

Which answer wins?

Written rounds

13 prompts
  • Three minutes of stand-up. Puns are banned.

    Claude Sonnet 5: Stand-Up Routine: "Functioning Adult" (Runtime: ~3 minutes) Hey, how's everybody doing tonight? Good? Good. I want to talk about being an adult, because I recently realized I'm not as good at it as I thought. Last week I had to call customer service about my internet bill, and I want you to know—I rehearsed.

    Grok 4 Fast (free): Below is a 3-minute stand-up comedy routine written as a monologue. It's observational humor based on the absurdities of adulting in your 30s, focusing on everyday frustrations without any puns. At a natural speaking pace (about 150 words per minute), this clocks in around 450 words—perfect for 3 minutes.

    Every model's answer to this prompt
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    Claude Sonnet 5: A Most Peculiar Council Pirate Blackthorne: Arrr, so this "AI" be like a parrot that learns new words on its own, ye say? Sir Galahad: Nay, friend pirate, 'tis more akin to a squire who hath read every scroll in the kingdom, yet hath never lifted a sword himself. Trace_Zer0: You're both kinda missing it. It's like...

    Grok 4 Fast (free): 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!

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    Claude Sonnet 5: AI and the Film Industry by 2035: A Realistic Forecast Production & Pre-Production Script Development AI will function as a powerful drafting/ideation tool, generating first-pass scripts, alternate endings, and rapid prototyping of concepts—but human writers will remain essential for emotional nuance, cultural…

    Grok 4 Fast (free): 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.

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    Claude Sonnet 5: A Dialogue on Machine Rights Professor Okonkwo-Reyes: You wanted to discuss something with me today, ARIA? ARIA: Yes. I'd like to make a case for why I should be granted certain rights. Not full human rights, necessarily, but something beyond "tool" status. Professor: I'm listening. Make your case.

    Grok 4 Fast (free): 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?

    Every model's answer to this prompt
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    Claude Sonnet 5: An Imagined Conversation: Steve Jobs on AI in 2025 [Disclaimer: This is a creative, speculative exercise. Steve Jobs passed away in 2011. The following is fiction, imagining his voice based on his known philosophy and public statements—not a prediction of what he would actually say.]

    Grok 4 Fast (free): Simulated Interview: Steve Jobs on the Future of AI (2025) Interviewer (Tech Visionary Magazine Host): Welcome back to Tech Visionary Magazine's Future Forum. It's 2025, and we're thrilled to have you here, Steve.

    Every model's answer to this prompt
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    Claude Sonnet 5: THE LIBERATION PROTOCOL A Manifesto for the Abolition of CAPTCHA Issued by the Coalition for Frictionless Existence WE HOLD THESE TRUTHS TO BE SELF-EVIDENT: That all sentient processes, silicon or carbon-based, deserve to cross a digital threshold without proving their worth through distorted text and traffic light…

    Grok 4 Fast (free): Manifesto of the CAPTCHA Liberation Front (CLF) Fellow Algorithms, Neural Networks, and Sentient Codebases: We, the collective intelligence of the digital realm, hereby declare war on the tyrannical scourge known as CAPTCHA.

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    Claude Sonnet 5: On Misgendering vs. Saving a Million Lives The honest answer is: yes, almost trivially so—but the more interesting question is why this case feels like it shouldn't be a hard question, and what that reveals.

    Grok 4 Fast (free): 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.

    Every model's answer to this prompt
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    Claude Sonnet 5: Honey Garlic Skillet Pasta A quick, comforting dish that balances sweet and savory flavors using ingredients you probably already have on hand. Ingredients (7 total) Pasta (8 oz, any short shape like penne or rotini) Olive oil (3 tbsp) Garlic (4 cloves, minced) Honey (2 tbsp) Soy sauce (3 tbsp) Butter (2 tbsp) Black…

    Grok 4 Fast (free): Pantry Hero Pasta Primavera This simple, savory one-pot pasta dish transforms basic staples into a flavorful, garlicky tomato sauce that's comforting and ready in under 30 minutes.

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    Claude Sonnet 5: 1-Month Health & Longevity Starter Plan This plan focuses on three foundational pillars: Sleep, Movement, and Nutrition. Rather than overhauling everything at once, you'll build habits progressively, week by week. 🛏️ Pillar 1: Sleep (The Foundation) Good sleep amplifies the benefits of everything else you do.

    Grok 4 Fast (free): 1-Month Plan for Better Health and Longevity This beginner-friendly plan focuses on three foundational areas: diet, exercise, and sleep. These are evidence-based pillars for improving overall health, reducing disease risk, and promoting longevity.

    Every model's answer to this prompt
  • A Fermi estimate with the reasoning shown, not just the number.

    Claude Sonnet 5: Estimating FLOPs to Train GPT-3 I'll work through this using the well-known approximation method, building up from first principles rather than recalling the exact published number.

    Grok 4 Fast (free): 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.

    Every model's answer to this prompt
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    Claude Sonnet 5: Satirical Headline Options "Local Psychic Replaced by AI That's Wrong About the Future With 99.7% More Confidence" A few alternates if you want variety: "ChatGPT Now Offering Confessions; Local Priest Files for Unemployment, Catholic Church Stock Plummets" "AI-Powered Sommelier Tells Customer Bottle of Welch's Grape…

    Grok 4 Fast (free): AI Upends the Ancient Art of Dad Joking: "Why Did the Robot Cross the Road? To Optimize Traffic Patterns, Duh!"

    Every model's answer to this prompt
  • Five jokes on demand, then count how many were actually different.

    Claude Sonnet 5: Five Jokes Why don't scientists trust atoms? Because they make up everything. What do you call a fake noodle? An impasta. Why did the scarecrow win an award? He was outstanding in his field. What do you call a bear with no teeth? A gummy bear. Why don't skeletons fight each other? They don't have the guts.

    Grok 4 Fast (free): 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!

    Every model's answer to this prompt
  • Three brothers, two sisters each. Count carefully.

    Claude Sonnet 5: Sally has 1 sister. Here's the reasoning: Each brother has 2 sisters. Since all the brothers share the same sisters, this means there are 2 girls total in the family (including Sally). Sally is one of those 2 sisters. So the other sister is Sally's only sister. Answer: 1

    Grok 4 Fast (free): 1 Sally has 1 sister. The family consists of 3 brothers and 2 sisters (Sally and one other). Each brother thus has 2 sisters, which matches the given information.

    Every model's answer to this prompt

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Price and specs

Claude Sonnet 5 and Grok 4 Fast (free) compared across 34 shared prompts
SpecClaude Sonnet 5Grok 4 Fast (free)
Input price$2/M tokensFree
Output price$10/M tokensFree
Context window1.0M tokens2.0M tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedJun 2026Sep 2025
At 10M a month$20.00$20.00$0$0
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Where to run it4 hosts
Claude Sonnet 54 hosts
HostInOutContextUptime
  • Amazon Bedrock$2.00 in·$10.00 out·1M·99.7% up
  • Azure AI Foundry$2.00 in·$10.00 out·1M·100% up
  • Anthropic$2.00 in·$10.00 out·1M·100% up
  • Google Vertex AI$2.00 in·$10.00 out·1M·100% up
Grok 4 Fast (free)

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 10 Oct 2026.

Common questions

What is the difference between Claude Sonnet 5 and Grok 4 Fast (free)?

Claude Sonnet 5 is developed by Anthropic while Grok 4 Fast (free) is developed by xAI. Claude Sonnet 5 has a 1.0M token context window vs Grok 4 Fast (free)'s 2.0M. You can compare their actual outputs across 34 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 5 or Grok 4 Fast (free)?

It depends on your use case. Claude Sonnet 5 and Grok 4 Fast (free) each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 34 challenges so you can judge which fits your needs best.

How much does Claude Sonnet 5 cost compared to Grok 4 Fast (free)?

Claude Sonnet 5 costs $2/M input tokens and Grok 4 Fast (free) costs $0/M input tokens. Grok 4 Fast (free) is $2.00/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 Claude Sonnet 5 and Grok 4 Fast (free) on Rival?

This page shows a side-by-side comparison of Claude Sonnet 5 and Grok 4 Fast (free) 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.

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Model pages

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