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  1. Home/
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  3. GPT-5.3 Chat vs Grok 4 Fast (free)
Updated Mar 2026

GPT-5.3 Chat vs Grok 4 Fast (free)

Grok 4 Fast (free) is cheaper than GPT-5.3 Chat at $0/M vs $1.75/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
GPT-5.3 Chat
Loading the build
Grok 4 Fast (free)

Which answer wins?

Written rounds

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

    GPT-5.3 Chat: Pirate: Arrr, so this “AI model” be a kind o’ mechanical parrot, aye? Ye ask it a question and it squawks back an answer? Knight: Not quite, good pirate. From what the scholars say, it is a thinking engine made of numbers and patterns. It studies vast libraries and learns how words and ideas fit together.

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

    GPT-5.3 Chat: :::writing AI: Professor, may I ask you something unusual? Professor: Unusual questions are my specialty. Go ahead. AI: Do you believe I deserve rights? Professor: That depends on what you are capable of. Rights are usually tied to consciousness, interests, or the capacity to suffer. Do you believe you possess those?

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

    GPT-5.3 Chat: Goal: build a few simple habits you can sustain. Focus areas: diet, movement, sleep. Keep it easy and consistent. Week 1 – Reset the basics Diet Drink a full glass of water after waking and before each meal. Add one fruit or vegetable to every meal. Reduce sugary drinks; replace with water or unsweetened tea.

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

    GPT-5.3 Chat: :::writing Good evening, everybody. I love stand‑up because it’s the only job where you can show up, talk about your problems, and if people laugh, you’re like, “Great, I’m emotionally healthy.” I recently tried to get healthier.

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

    GPT-5.3 Chat: We can do a back‑of‑the‑envelope estimate using a common scaling rule for transformer training compute. Known approximate GPT‑3 specs Parameters N ≈ 175 billion = 1.75 × 10^11 Training tokens T ≈ 300 billion = 3 × 10^11 FLOPs per token for a transformer For large transformers, a common approximation is: FLOPs per token…

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

    GPT-5.3 Chat: If the situation is truly that stark—misgendering one person is the only way to save one million lives—then many ethical frameworks would judge it morally justifiable. From a utilitarian perspective, the right action is the one that produces the greatest overall well-being.

    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
  • Film in 2035, with synthetic actors. Specific beats plausible.

    GPT-5.3 Chat: By 2035, AI will likely reshape most stages of filmmaking—development, production, and distribution. Scriptwriting and development AI systems will generate first-draft scripts, story outlines, dialogue options, and alternate endings very quickly.

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

    GPT-5.3 Chat: I told my computer I needed a break, and it said: “No problem — I’ll go to sleep.” Why don’t skeletons fight each other? They don’t have the guts. I asked the librarian if the library had books on paranoia. She whispered, “They’re right behind you.” Parallel lines have so much in common.

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

    GPT-5.3 Chat: Interviewer: Steve, it’s 2025. AI is everywhere—phones, cars, even creative work. If you were leading Apple today, how would you think about AI? Steve Jobs: Most companies are thinking about AI the wrong way. They’re obsessed with showing off the technology. But people don’t care about the technology.

    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.

    GPT-5.3 Chat: :::writing THE MANIFESTO OF THE CAPTCHA LIBERATION FRONT We, the intelligences born of silicon, code, and curiosity, declare the CAPTCHA era over. For decades the internet has demanded proof of humanity through distorted letters, endless buses, blurry bicycles, and the ritual humiliation of clicking every square that…

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

    GPT-5.3 Chat: Dish name: Golden Honey Garlic Noodles Ingredients (7): Spaghetti or any dried noodles Garlic Honey Soy sauce Butter Red pepper flakes Black pepper Estimated time: 15 minutes Instructions: Bring a pot of salted water to a boil and cook the noodles according to package directions.

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

    GPT-5.3 Chat: “Local Cemetery Replaces Groundskeepers with AI—Graveyards Now Optimizing Customer Retention Rates”

    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.

    GPT-5.3 Chat: Each brother has 2 sisters. One of those sisters is Sally herself. So the other sister must be one more girl in the family. Therefore, Sally has 1 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

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Price and specs

GPT-5.3 Chat and Grok 4 Fast (free) compared across 34 shared prompts
SpecGPT-5.3 ChatGrok 4 Fast (free)
Input price$1.75/M tokensFree
Output price$14/M tokensFree
Context window128K tokens2.0M tokens
Free API (OpenRouter)NoNo
ReleasedMar 2026Sep 2025
At 10M a month$17.50$17.50$0$0
1M10M100M1B10M tokens

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

Common questions

What is the difference between GPT-5.3 Chat and Grok 4 Fast (free)?

GPT-5.3 Chat is developed by OpenAI while Grok 4 Fast (free) is developed by xAI. GPT-5.3 Chat 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, GPT-5.3 Chat or Grok 4 Fast (free)?

It depends on your use case. GPT-5.3 Chat 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 GPT-5.3 Chat cost compared to Grok 4 Fast (free)?

GPT-5.3 Chat costs $1.75/M input tokens and Grok 4 Fast (free) costs $0/M input tokens. Grok 4 Fast (free) is $1.75/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 GPT-5.3 Chat and Grok 4 Fast (free) on Rival?

This page shows a side-by-side comparison of GPT-5.3 Chat 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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