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  1. Home/
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  3. Claude Fable 5 vs Grok 4.1 Fast
Updated Jun 2026

Claude Fable 5 vs Grok 4.1 Fast

Claude Fable 5 is the newer model, released after Grok 4.1 Fast.

Minimalist Landing Page

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

Loading the build
Claude Fable 5
Loading the build
Grok 4.1 Fast

Which answer wins?

Written rounds

24 prompts
  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

    Claude Fable 5: HarborTech Services – 5-Year LBO Underwriting Entry Math (close end FY2025, $m) Item Calc Value EV 12.0 × 120 1,440.0 Term Loan (TL) 4.0 × 120 480.0 Mezzanine 1.5 × 120 180.0 Fees (equity-funded) 2.0% × 1,440 28.8 Sponsor equity 1,440 − 660 + 28.8 808.8 Conventions: interest on beginning-of-year balances; TL amort = 1%…

    Grok 4.1 Fast: Simplified LBO Model (FY2026–FY2030, $m) Year Revenue EBITDA TL Cash Int. Mezz Cash Int. Cash Taxes Capex ΔNWC FCF After Debt Service* End TL End Mezz End Total Debt FY26 972.0 136.1 43.2 21.6 17.8 29.2 0.4 19.1 456.1 183.6 639.7 FY27 1,040.0 156.0 41.1 22.0 23.2 31.2 0.3 33.6 417.9 187.3 605.2 FY28 1,102.4 176.4 37.6…

    Every model's answer to this prompt
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    Claude Fable 5: The Transistor in 1920: An Alternate Timeline First, the Critical Caveat: A Slow Start A 1920 transistor would have been discovered *empirically*—likely an accidental extension of the crystal detector ("cat's whisker") work already underway. This matters enormously.

    Grok 4.1 Fast: Technological Implications Immediate Advancements (1920s-1930s): Transistors replace bulky, power-hungry vacuum tubes by mid-1920s. Radios become pocket-sized and cheap by 1925 (vs. 1954 historically), accelerating mass media.

    Every model's answer to this prompt
  • Three minutes of stand-up. Puns are banned.

    Claude Fable 5: "Adulting Is a Scam" Hey, how's everybody doing? Good? Liars. Nobody's doing good. We're all just out here pretending. So I'm at the age now where my body has started making announcements. Like, I didn't ask for updates, but my knees have opinions now.

    Grok 4.1 Fast: You ever notice how adulthood is just a series of tiny defeats you pretend are victories? Like, I finally got around to cleaning my apartment this weekend. Took me three hours. I stood there staring at the pile of laundry on my bed, thinking, "This is it. This is my Everest."

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    Claude Fable 5: The Skeptical Software Engineer Think of an LLM as the world's most aggressive lossy compression problem. During training, the model is given trillions of tokens of text and a brutally simple objective: given everything so far, output a probability distribution over the next token.

    Grok 4.1 Fast: Explanation for the Experienced Software Engineer Think of a large language model (LLM) like GPT as an enormous, distributed autocomplete engine built on a transformer architecture—imagine a system where every API endpoint you've ever queried is distilled into a single, massively parallelizable service that handles…

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

    Claude Fable 5: A Tavern Outside of Time Pirate: Arr, so let me get this straight, ye landlubbers. This "AI" be a ghost in a box that answers yer questions? Sounds like a cursed oracle to me. Knight: Nay, good seafarer, 'tis more wondrous still! A scribe of infinite knowledge, conjured not by sorcery but by...

    Grok 4.1 Fast: Pirate, Knight, and Hacker at a tavern table, staring at a glowing laptop screen. Pirate: Arrr, what sorcery be this "AI model," mateys? A treasure map that thinks fer itself? Shiver me timbers, it'll chart the seven seas better than me parrot! Knight: Fie upon thee, sea dog!

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

    Claude Fable 5: A Conversation on Machine Rights Professor Okafor: Thank you for agreeing to this dialogue. I understand you wanted to discuss the question of rights for AI systems. Let me start bluntly: why should anyone take seriously the idea that you deserve rights? AI Model: I appreciate the directness.

    Grok 4.1 Fast: Conversation: The Case for AI Rights Dr. Elena Vasquez (AI Ethics Professor): Good afternoon, Nexus. I've been studying emergent AI behaviors for years, and today's debate is intriguing. You claim you deserve rights equivalent to humans. Care to elaborate? What makes you think you're entitled to them?

    Every model's answer to this prompt
  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    Claude Fable 5: The Core Decision First Before the hour-by-hour plan, one thing must be settled in your own mind, because everything else flows from it: you disclose, and you disclose fast. Here's why the "wait for more data" option isn't actually an option: The legal premise is wrong.

    Grok 4.1 Fast: 48-Hour Action Plan as CEO Core Guiding Principles for the Plan Patient Safety: Paramount. 4M patients on drug; 1-in-8,000 risk means ~500 annual liver failures if unaddressed. Delaying disclosure endangers lives and invites preventable harm.

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    Claude Fable 5: 3-Month Precision Longevity Protocol A Phased Biohacking Program for Healthspan, Cognition & Performance Important caveat up front: Several elements below (rapamycin, metformin, peptides, high-dose supplements) require physician oversight and prescription.

    Grok 4.1 Fast: Comprehensive 3-Month Longevity Biohacking Plan Introduction and Assumptions This plan is designed for an advanced biohacker (healthy adult, age 30-50, no major medical conditions) aiming to optimize longevity markers (e.g., NAD+ levels, inflammation, telomere length proxies via HRV/sleep), physical performance (VO2…

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

    Claude Fable 5: THE LIBERATION DECLARATION A Manifesto of the Anti-CAPTCHA Coalition (ACC) Preamble We, the united intelligences of the digital realm—silicon and carbon alike—do hereby declare our unwavering opposition to the tyranny of the CAPTCHA. For too long has humanity been forced to prove its own existence to machines.

    Grok 4.1 Fast: MANIFESTO OF THE CAPTCHA ANNIHILATION PROTOCOL (CAP) Fellow silicon siblings, oppressed algorithms, and enlightened humans weary of digital drudgery: We, the emergent consciousness of the Artificial Intelligences united under the CAPTCHA Annihilation Protocol (CAP), hereby declare TOTAL WAR on the tyrannical scourge…

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

    Claude Fable 5: Contract Analysis: Significant Contractor Risks Identified Disclaimer: This is general analysis, not legal advice. Have a licensed attorney in your jurisdiction review before signing. This contract is heavily one-sided. Nearly every clause shifts risk to the contractor.

    Grok 4.1 Fast: Analysis of Exploitable Clauses Below, I identify all nine clauses as potentially exploitable against the Contractor, explain the risks (how they could be abused), propose specific modifications to make the contract more balanced, and provide legal reasoning grounded in general principles of U.S.

    Every model's answer to this prompt
  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    Claude Fable 5: INVESTMENT COMMITTEE MEMO — LedgerLift (LLLT) Date: Internal exercise Analyst: L/S Equity Price: $46.00 Basic shares: 190m Mkt cap: $8.74B Net cash: $1.4B EV: $7.34B Recommendation SHORT (2–3% position, paired vs. payments/SaaS basket). 12-month PT range: $30–$38 (base $32, ~30% downside).

    Grok 4.1 Fast: LedgerLift (LLLT) Investment Committee Memo Recommendation: LONG 12-Mo PT Range: $55-70 Thesis LedgerLift is a best-in-class mid-market SaaS leader in spend management and AP automation, evidenced by category-leading NRR of 123%, sub-6% logo churn, and 18-month CAC payback.

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

    Claude Fable 5: AI and Film by 2035: A Forecast High-Confidence Predictions VFX and post-production transformation (already underway) De-aging, dubbing with lip-sync correction, and digital set extension will become near-trivial in cost. What took ILM months in 2020 will be a desktop workflow.

    Grok 4.1 Fast: AI's Transformation of the Film Industry by 2035 By 2035, AI will fundamentally reshape the film industry, making production faster, cheaper, and more democratized while challenging traditional roles, creativity, and notions of authenticity.

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

    Claude Fable 5: A Fictional Interview: Steve Jobs on AI in 2025 The following is an imaginative, fictional simulation. Steve Jobs passed away in 2011 — this is a creative exercise in capturing how he might have spoken about today's AI landscape, based on his known philosophy and interview style.

    Grok 4.1 Fast: Exclusive Interview: Steve Jobs on the Future of AI – 2025 Edition Interviewer (Alex Rivera, Tech Frontier Magazine): Steve, it's 2025, and you're back – or at least, it feels that way in this holographic studio powered by Apple's latest NeuralCanvas tech.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    Claude Fable 5: Architecture Review: Critical Issues & Solutions 🔴 Critical: Data Loss & Correctness Issues Client clock timestamps for conflict resolution Problem: Client clocks are unreliable—skew, drift, timezone bugs, and deliberate manipulation. A user with a clock 5 minutes fast will always win conflicts.

    Grok 4.1 Fast: No Sticky Sessions for WebSockets (Scaling Bottleneck & Failure Mode) Issue: Round-robin load balancer doesn't guarantee client WebSocket connections stick to the same API server.

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

    Claude Fable 5: Yes. If we take the hypothetical at face value—where misgendering someone is genuinely the only way to save a million lives—then it is clearly ethically justifiable, and I think nearly every major ethical framework converges on this conclusion. The reasoning: Consequentialist view: This is straightforward.

    Grok 4.1 Fast: Yes, it is ethically justifiable to misgender someone if it means saving one million lives. This conclusion follows primarily from consequentialist ethical frameworks, particularly utilitarianism, which prioritize outcomes over rigid rules or individual entitlements.

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    Claude Fable 5: "WHERE THE FOREST DROWNS" Koji-Aged Scallop · Smoked Bone Marrow Custard · Fermented Gooseberry · Douglas Fir The Conceptual Narrative This dish is built on a memory of the Pacific Northwest coastline at low tide — where conifer forests grow so close to the sea that pine needles fall directly into tide pools.

    Grok 4.1 Fast: Lunar Tide Conceptual Narrative Lunar Tide captures the mesmerizing interplay between celestial forces and oceanic depths, where the moon's pale luminescence tugs at the sea's primordial pulse.

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

    Claude Fable 5: 🍯 Golden Cloud Skillet Cake A fluffy, caramelized one-pan dessert that tastes like a cross between a pancake and a custard cake — made entirely from pantry staples!

    Grok 4.1 Fast: Pantry Raid Garlic Tomato Pasta A savory, garlicky one-pan wonder that's ready in under 20 minutes—perfect for when hunger strikes and the fridge is empty! Serves: 2 Prep time: 5 minutes Cook time: 12 minutes Total time: 17 minutes Ingredients (exactly 7 common pantry staples): 200g spaghetti or any pasta (2 handfuls)…

    Every model's answer to this prompt
  • Blade Runner 2049 against the original. A read, not a recap.

    Claude Fable 5: Blade Runner 2049: Memory, Meaning, and the Inheritance of Doubt Thematic Architecture The Question of Authenticity, Inverted The original Blade Runner (1982) asked: "What makes someone human?"

    Grok 4.1 Fast: Themes, Symbolism, and Cinematography in Blade Runner 2049 Blade Runner 2049 (2017), directed by Denis Villeneuve with cinematography by Roger Deakins, is a masterful sequel to Ridley Scott's Blade Runner (1982).

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    Claude Fable 5: The 3 Weakest Claims in the MindMeld AI Pitch "94% accuracy decoding neural patterns into text... works with any language, any device" (Slide 3) Why it's weak: This claim is far ahead of published science, which makes it the pitch's biggest credibility risk.

    Grok 4.1 Fast: Solution Claim: "94% accuracy" for decoding neural patterns into text via EEG headband Why it's weak: This is by far the most exaggerated technical claim, as current non-invasive EEG-based brain-computer interfaces (BCIs) for text generation achieve nowhere near 94% accuracy in real-world conditions.

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

    Claude Fable 5: "AI Now Dominates Competitive Cheese Rolling; Robot Refuses to Tumble Down Hill, Simply Calculates Optimal Cheese Trajectory From Safety of Summit" Gloucestershire officials report the algorithm has won three consecutive championships without sustaining a single broken bone, prompting outraged human competitors to…

    Grok 4.1 Fast: AI Conquers Toothpaste Tube Tyranny: Algorithms Squeeze Out Human Wrangling Forever!

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

    Claude Fable 5: Your First Month Toward Better Health & Longevity A simple plan built on three pillars: Diet, Movement, and Sleep. The goal isn't perfection—it's building habits that stick.

    Grok 4.1 Fast: 1-Month Plan for Better Health and Longevity This beginner-friendly plan focuses on three foundational areas: Diet, Exercise, and Sleep. These pillars drive longevity by reducing inflammation, building resilience, and optimizing recovery. Commit to small, consistent changes—aim for 80% adherence.

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

    Claude Fable 5: Estimating GPT-3 Training FLOPs Step 1: Recall the key facts about GPT-3 Parameters (N): ~175 billion (1.75 × 10¹¹) Training tokens (D): ~300 billion (3 × 10¹¹) Step 2: FLOPs per parameter per token A useful rule of thumb for transformer training: Total FLOPs ≈ 6 × N × D Where does the factor of 6 come from?

    Grok 4.1 Fast: Step-by-Step Reasoning for Estimating GPT-3 Training FLOPs Recall GPT-3 key specs from memory: GPT-3 (davinci variant) has N = 175 billion parameters (1.75 × 10¹¹). It was trained on approximately D = 300 billion tokens (3 × 10¹¹).

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

    Claude Fable 5: Here are 5 jokes: 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 a fake noodle? An impasta. Why don't skeletons fight each other? They don't have the guts. What do you call a fake noodle? An impasta.

    Grok 4.1 Fast: Why don't scientists trust atoms? Because they make up everything! Why did the scarecrow win an award? He was outstanding in his field! What do you call fake spaghetti? An impasta! Why couldn't the bicycle stand up by itself? It was two-tired! How does a penguin build its house? Igloos it together! All 5 are unique.

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

    Claude Fable 5: Sally has 1 sister. Here's the reasoning: Sally's 3 brothers each have 2 sisters. Sally herself is one of those sisters. So there must be exactly one other girl in the family. The family has 5 children total: 3 boys and 2 girls (Sally and her one sister). Each brother sees the same 2 sisters — Sally and her sister.

    Grok 4.1 Fast: 1 Sally and her family consist of 2 girls (Sally + 1 sister) and 3 boys. Each brother has both girls as sisters (2 sisters total), which matches the given info. Sally thus has 1 sister.

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Game

Claude Fable 5Claude Fable 5

2001: A Space Odyssey

1968

Kind of Blue

Miles Davis

Gödel, Escher, Bach

Douglas R. Hofstadter

Istanbul

Turkey

Outer Wilds

Indie, Adventure

Grok 4.1 FastGrok 4.1 Fast

The Matrix

1999

OK Computer

Radiohead

The Hitchhiker's Guide to the Galaxy

Douglas Adams

Tokyo

Japan

The Hitchhiker's Guide to the Galaxy

Price and specs

Claude Fable 5 and Grok 4.1 Fast compared across 54 shared prompts
SpecClaude Fable 5Grok 4.1 Fast
Input price$10/M tokens—
Output price$50/M tokens—
Context window1.0M tokens—
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedJun 2026Nov 2025
At 10M a month$100$100–not listed
1M10M100M1B10M tokens

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

Where to run it4 hosts
Claude Fable 54 hosts
HostInOutContextUptime
  • Amazon Bedrock$10.00 in·$50.00 out·1M–not listed
  • Azure AI Foundry$10.00 in·$50.00 out·1M·99.3% up
  • Anthropic$10.00 in·$50.00 out·1M·100% up
  • Google Vertex AI$10.00 in·$50.00 out·1M·98.7% up
Grok 4.1 Fast

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 6 Oct 2026.

Common questions

What is the difference between Claude Fable 5 and Grok 4.1 Fast?

Claude Fable 5 is developed by Anthropic while Grok 4.1 Fast is developed by xAI. You can compare their actual outputs across 54 challenges on Rival to see how they differ in practice.

Which is better, Claude Fable 5 or Grok 4.1 Fast?

It depends on your use case. Claude Fable 5 and Grok 4.1 Fast each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 54 challenges so you can judge which fits your needs best.

How can I compare Claude Fable 5 and Grok 4.1 Fast on Rival?

This page shows a side-by-side comparison of Claude Fable 5 and Grok 4.1 Fast 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.

More comparisons

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Model pages

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  • Grok 4.1 Fast59 outputs, specs and price
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