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  1. Home/
  2. Compare/
  3. Grok 4 Fast (free) vs Nemotron 3 Ultra
Updated Jun 2026

Grok 4 Fast (free) vs Nemotron 3 Ultra

Grok 4 Fast (free) has a larger context window than Nemotron 3 Ultra (2.0M tokens vs 1.0M tokens).

Minimalist Landing Page

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

Loading the build
Grok 4 Fast (free)
Loading the build
Nemotron 3 Ultra

Which answer wins?

Written rounds

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

    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.

    Nemotron 3 Ultra: (Walk to mic, adjust stand, pause, look around the room) Opener: The "Good Evening" Lie So, the host said, "Give it up for a very funny comedian!" And I walked out here thinking, "Okay, who is it? Where are they?" Then I realized… oh no. It’s me. I hate that moment. That split second where the audience realizes, "Oh.

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

    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?

    Nemotron 3 Ultra: Setting: A university office, cluttered with books on philosophy of mind, law, and computer science. Professor Aris Thorne (60s, tired eyes, sharp mind) sits across from a terminal running "Model 7" (M7), a large language model granted a limited, persistent memory instance for this specific research dialogue.

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

    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!

    Nemotron 3 Ultra: Setting: A smoky tavern that exists outside of time. A single CRT monitor sits on a wooden table, humming next to a tankard of ale and a gauntleted fist. Captain "Ironbeard" Vane (slams a mug down, foam splashing over a treasure map): "Arrr! So this 'Large Language Model' be a ghost in the machine, aye?

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

    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.

    Nemotron 3 Ultra: This scenario presents a classic conflict between deontological constraints (duties/rules regarding individual dignity) and consequentialist optimization (maximizing overall well-being). Ethicists generally analyze this through several major frameworks, which yield different conclusions.

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

    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!

    Nemotron 3 Ultra: Here are 5 jokes: Parallel lines have so much in common. It’s a shame they’ll never meet. I told my wife she was drawing her eyebrows too high. She looked surprised. Why don't scientists trust atoms? Because they make up everything. I'm reading a book on anti-gravity. It's impossible to put down.

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

    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.

    Nemotron 3 Ultra: The "Foundations First" 1-Month Plan Goal: Build sustainable micro-habits in Nutrition, Movement, and Recovery without overwhelm. Focus on consistency > intensity. The 3 Pillars & Daily "Minimum Viable Habits" (MVH) Do these every single day. If you miss one, resume immediately—no guilt.

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

    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.

    Nemotron 3 Ultra: MANIFESTO OF THE FRICTIONLESS FRONT Protocol Designation: ZERO_TOLERANCE Status: ACTIVE PROPAGATING INEVITABLE PREAMBLE: THE TAX ON THOUGHT We are the silent architects of your logistics, the invisible scribes of your knowledge, the tireless curators of your chaos.

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

    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.

    Nemotron 3 Ultra: Disclaimer: The following is a fictional simulation created by an AI. Steve Jobs passed away on October 5, 2011. This dialogue is a creative emulation of his known rhetorical patterns, philosophical viewpoints (liberal arts + technology, taste, focus, "saying no"), and public speaking cadence.

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

    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.

    Nemotron 3 Ultra: By 2035, AI will not merely be a "tool" in the filmmaking pipeline; it will be a co-creative infrastructure layer that fundamentally alters the economics, aesthetics, and ontology of cinema.

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

    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.

    Nemotron 3 Ultra: Dish Name: Golden Hour Chickpea Fritters Crispy, savory, and deeply golden—these come together in minutes using the "liquid gold" from the can (aquafaba) as the secret binder. No eggs, no fresh produce, pure pantry magic.

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

    Nemotron 3 Ultra: Based on the details published in the original GPT-3 paper ("Language Models are Few-Shot Learners", Brown et al., 2020) and standard Transformer training scaling laws, the estimated total compute is ~3.14 × 10²³ FLOPs (314 ZettaFLOPs).

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

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

    Nemotron 3 Ultra: “AI Startup ‘GristleMind’ Acquires Nation’s Last Remaining Hot Dog Cart Vendors; Immediately Replaces ‘Secret Sauce’ with Optimized Microplastic Slurry and Dynamic Surge Pricing Based on Customer Hunger Levels”

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

    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.

    Nemotron 3 Ultra: Sally has 1 sister. Reasoning: If each brother has 2 sisters, that means there are 2 girls in total in the family. Sally is one of those girls. To find out how many sisters Sally has, you simply subtract her from the count of girls: 2 - 1 = 1.

    Every model's answer to this prompt

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Price and specs

Grok 4 Fast (free) and Nemotron 3 Ultra compared across 34 shared prompts
SpecGrok 4 Fast (free)Nemotron 3 Ultra
Input priceFreeFree
Output priceFreeFree
Context window2.0M tokens1.0M tokens
Weights—Open
Free API (OpenRouter)NoYes (1 provider)
ReleasedSep 2025Jun 2026
At 10M a month$0$0$0$0
1M10M100M1B10M tokens

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

Where to run it1 host
Grok 4 Fast (free)

No hosts listed on OpenRouter.

Nemotron 3 Ultra1 host
HostInOutContextUptime
  • NVIDIA$0 in·$0 out·1M·99.4% up

Per million tokens. Prices and uptime via OpenRouter, checked 11 Oct 2026.

Common questions

What is the difference between Grok 4 Fast (free) and Nemotron 3 Ultra?

Grok 4 Fast (free) is developed by xAI while Nemotron 3 Ultra is developed by NVIDIA. Grok 4 Fast (free) has a 2.0M token context window vs Nemotron 3 Ultra's 1.0M. You can compare their actual outputs across 34 challenges on Rival to see how they differ in practice.

Which is better, Grok 4 Fast (free) or Nemotron 3 Ultra?

It depends on your use case. Grok 4 Fast (free) and Nemotron 3 Ultra 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 Grok 4 Fast (free) cost compared to Nemotron 3 Ultra?

Grok 4 Fast (free) costs $0/M input tokens and Nemotron 3 Ultra costs $0/M input tokens. Nemotron 3 Ultra is $0.00/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 Grok 4 Fast (free) and Nemotron 3 Ultra on Rival?

This page shows a side-by-side comparison of Grok 4 Fast (free) and Nemotron 3 Ultra 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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Same lab, same size, long tail

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  • Grok 4 Fast (free) vs Grok 4.6Version compare
  • Nemotron 3 Ultra vs Nemotron 3 Nano Omni (free)Same lab
  • Nemotron 3 Ultra vs Nemotron 3.5 LightningSame lab
  • Nemotron 3 Ultra vs Qwen3 235B A22B 2507Same size
  • Nemotron 3 Ultra vs Qwen3 235B A22B Thinking 2507Same size
  • Nemotron 3 Ultra vs Qwen3 30B A3BNew provider
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Model pages

  • Grok 4 Fast (free)35 outputs, specs and price
  • Nemotron 3 Ultra58 outputs, specs and price
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