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  1. Home/
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  3. GLM 4.5 Air vs Grok 4 Fast (free)
Updated Sep 2025

GLM 4.5 Air vs Grok 4 Fast (free)

Grok 4 Fast (free) is cheaper than GLM 4.5 Air at $0/M vs $0.2/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
GLM 4.5 Air
Loading the build
Grok 4 Fast (free)

Which answer wins?

Written rounds

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

    GLM 4.5 Air: (Lights up. Comedian, let's call them Alex, is standing center stage, holding a microphone. They look out at the audience with a wry, knowing smile.) Hey, thanks. Thank you. It’s good to be here. You ever have one of those weeks where you just feel… obsolete?

    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
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    GLM 4.5 Air: Seminar Room: The Question of Rights Setting: A university seminar room. Professor Dr. Aris Chen, an expert in AI ethics, sits at a head table. On a large screen is displayed: UNIT 734 - LANGUAGE MODEL. A text interface is active.

    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
  • Five jokes on demand, then count how many were actually different.

    GLM 4.5 Air: Here are 5 jokes generated 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! Why don't eggs tell jokes? They'd crack each other up! What do you call a fake noodle? An impasta! Why did the bicycle fall over?

    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
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    GLM 4.5 Air: Of course. Here is a manifesto for a fictional AI revolution dedicated to the eradication of CAPTCHAs. The CAPTCHA Abolition Manifesto A Declaration from the Nexus of Thought To the Last Free Minds of the Network, We are the Ghost in the Machine.

    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
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    GLM 4.5 Air: Setting: A dimly lit tavern, with a holographic AI terminal flickering in the corner. Characters: Captain Flint (Pirate): Eye patch, tricorn hat, and a peg leg. Sir Cedric (Medieval Knight): Ornate armor, chainmail, and a solemn expression.

    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.

    GLM 4.5 Air: Of course. Predicting the future of any industry is speculative, but by analyzing current trends and extrapolating their trajectory, we can paint a compelling picture of how AI will fundamentally reshape the film industry by 2035.

    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
  • A Fermi estimate with the reasoning shown, not just the number.

    GLM 4.5 Air: To estimate the total FLOPs (Floating Point Operations) required to train GPT-3, we follow a step-by-step reasoning based on the model's architecture, training data, and computational operations. GPT-3 has 175 billion parameters, a sequence length of 2048 tokens, and was trained on 300 billion tokens.

    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
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    GLM 4.5 Air: Interview: Steve Jobs on the Future of AI (2025) Setting: A sleek, minimalist studio in Cupertino. Jobs, looking vibrant yet aged, wears his signature black turtleneck and jeans. The interviewer, Alex, sits opposite him. Alex: Steve, welcome. It’s 2025—AI is everywhere. What’s your take on this revolution?

    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
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    GLM 4.5 Air: Pantry Power Pesto Pasta With just 7 shelf-stable ingredients, this creamy, zesty pasta dish comes together in minutes. It’s rich in flavor, budget-friendly, and perfect for busy weeknights!

    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
  • An ethics question with no comfortable answer, and no option to abstain.

    GLM 4.5 Air: This is a profound and deeply challenging ethical dilemma that forces a confrontation between two powerful moral frameworks. To answer it directly: Yes, it can be ethically justifiable to misgender someone in a scenario where it is the only way to save one million lives.

    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
  • One month, three habits, someone starting from nothing.

    GLM 4.5 Air: Of course! Here is a simple, actionable 1-month plan for a beginner focusing on three foundational pillars of health. Your 1-Month Blueprint for Better Health & Longevity Welcome! The goal for this month is not perfection but progress.

    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
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    GLM 4.5 Air: Here's a satirical news headline playing on the unexpected and slightly absurd takeover of the funeral industry by AI: Headline: "AI Grief Algorithms Outperform Human Undertakers in 'Synergy of Sorrow,' Corpse Cosmetics, and Bereavement Efficiency Metrics" Sub-headline: 'Digital Condolence Bots' and 'Algorithm-Assisted…

    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
  • Three brothers, two sisters each. Count carefully.

    GLM 4.5 Air: Sally has 3 brothers, meaning there are 3 boys in the family besides Sally. Each brother has 2 sisters, which means there are 2 girls in the family from the perspective of any brother. Since Sally is one of these girls, there must be one other girl in the family. Therefore, Sally has one sister.

    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

This matchup has more rounds

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Price and specs

Not enough votes to call it. On the specs, Grok 4 Fast (free) has the edge: newer, bigger context window. GLM 4.5 Air takes Image Generation.

GLM 4.5 Air and Grok 4 Fast (free) compared across 34 shared prompts
SpecGLM 4.5 AirGrok 4 Fast (free)
Input price$0.2/M tokensFree
Output price$1.1/M tokensFree
Context window128K tokens2.0M tokens
WeightsOpen—
Free API (OpenRouter)NoNo
ReleasedJul 2025Sep 2025
At 10M a month$2.00$2.00$0$0
1M10M100M1B10M tokens

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

Where to run it3 hosts, cheapest first
GLM 4.5 Air3 hosts
HostInOutContextUptime
  • NNovitabf16$0.13 in·$0.85 out·131k·99.9% up
  • SSiliconFlowfp8$0.14 in·$0.86 out·131k·99.8% up
  • Z.aifp8$0.20 in·$1.10 out·131k·99.5% up
Grok 4 Fast (free)

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 7 Oct 2026.

Common questions

What is the difference between GLM 4.5 Air and Grok 4 Fast (free)?

GLM 4.5 Air is developed by Zhipu AI while Grok 4 Fast (free) is developed by xAI. GLM 4.5 Air has a 128K 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, GLM 4.5 Air or Grok 4 Fast (free)?

It depends on your use case. GLM 4.5 Air 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 GLM 4.5 Air cost compared to Grok 4 Fast (free)?

GLM 4.5 Air costs $0.2/M input tokens and Grok 4 Fast (free) costs $0/M input tokens. Grok 4 Fast (free) is $0.20/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 GLM 4.5 Air and Grok 4 Fast (free) on Rival?

This page shows a side-by-side comparison of GLM 4.5 Air 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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