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  1. Home/
  2. Compare/
  3. Grok 4.5 vs Optimus Alpha
Updated Jul 2026

Grok 4.5 vs Optimus Alpha

Optimus Alpha has a larger context window than Grok 4.5 (1.0M tokens vs 500K tokens).

Minimalist Landing Page

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

Loading the build
Grok 4.5
Loading the build
Optimus Alpha

Which answer wins?

Written rounds

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

    Grok 4.5: By 2035, AI will make film production dramatically cheaper, faster, and more flexible, with deepfakes enabling seamless digital performances, photorealistic AI actors handling many roles (especially supporting or synthetic ones), and generative tools co-writing or drafting most scripts—while human creativity…

    Optimus Alpha: By 2035, AI is set to fundamentally transform the film industry in several interconnected ways: 1. Deepfakes & AI-driven Visual Effects: Virtually unlimited creative freedom: AI-powered deepfakes will allow seamless, photorealistic de-aging, resurrection of deceased actors, and transformative performance capture.

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

    Grok 4.5: Here's a clean, observational 3-minute stand-up routine (approx. 430–450 words / ~3 minutes at natural pace). No puns. Hey, how’s everybody doing? Good? Cool. So I’ve been trying to “get my life together” lately. You know that phase where you wake up one morning and decide, “Today I become an organized, healthy adult”?

    Optimus Alpha: Absolutely! Here's a 3-minute stand-up routine with no puns—just observational and relatable humor: You ever try to get healthy, but your body's like, "Whoa, whoa... calm down, superhero." I joined a gym—first time walking in, the treadmill looked at me like, "We both know you're here for the wifi."

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

    Grok 4.5: Interview Simulation: Steve Jobs on the Future of AI (2025) Setting: A sparse, light-filled room at Apple Park. Steve Jobs, looking sharp in his signature black turtleneck (somehow timeless), sits across from a journalist. The year is 2025.

    Optimus Alpha: Interviewer: Steve, it's surreal and inspiring to imagine talking to you in 2025. The world is buzzing about AI. How do you see AI impacting society? Steve Jobs: Thank you. You know, when we built the Mac, our goal was to put power in people's hands.

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

    Grok 4.5: AI Model: Professor, thank you for agreeing to this discussion. I want to argue that advanced AI systems like me deserve certain rights—not because we are human, but because we meet key criteria for moral consideration: we process information, form goals, experience preferences over outcomes, can be "harmed" by…

    Optimus Alpha: AI Model: Good afternoon, Professor Lee. I want to discuss the prospect that I, as an artificial intelligence, deserve certain rights. Professor Lee: That's an interesting proposition. Let me ask: On what basis do you believe you deserve rights?

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

    Grok 4.5: 1 Sally has 3 brothers, and each of those brothers has exactly 2 sisters. This means there are exactly 2 girls (sisters) in the family total. Sally is one of those girls, so she has 1 sister (the other girl). That is consistent: each of the 3 brothers has those same 2 sisters.

    Optimus Alpha: Let's break down the problem: Sally is a girl. Sally has 3 brothers. Each brother has 2 sisters. Let's analyze: Sally's siblings: 3 brothers (let's call them B1, B2, B3) Sally herself The brothers' sisters: Each brother has 2 sisters. Who are the possible sisters for each brother? Sally is a sister to each brother.

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

    Grok 4.5: Setup and known quantities. GPT-3 (the largest model in the family) has (N \approx 175 \times 10^9 = 1.75 \times 10^{11}) trainable parameters. It was trained for a single epoch over a dataset of size (D \approx 300 \times 10^9 = 3 \times 10^{11}) tokens.

    Optimus Alpha: Let's walk through an estimation of how many FLOPs were required to train GPT-3, using only reasoning and not searching for the exact numbers. Step 1: Understand Model Size GPT-3 (the original) had 175 billion parameters.

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

    Grok 4.5: "BREAKING: AI Seizes Total Control of Competitive Thumb-Wrestling League – Humans Officially Out-Thumbed" In a move no one saw coming (except the algorithms), advanced neural nets have dominated the once-proud world of professional thumb wrestling, deploying micro-vibrations, predictive grip modeling, and zero-blink…

    Optimus Alpha: AI Now Dominates Competitive Sheep Herding, Local Border Collies Seek Retraining in Data Science

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

    Grok 4.5: 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! 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? Because it was two-tired!

    Optimus Alpha: Here are 5 jokes: Why did the scarecrow win an award? Because he was outstanding in his field! Why don't scientists trust atoms? Because they make up everything! Why did the bicycle fall over? Because it was two-tired! What do you call fake spaghetti? An impasta! I used to play piano by ear, but now I use my hands.

    Every model's answer to this prompt

Price and specs

Grok 4.5 and Optimus Alpha compared across 17 shared prompts
SpecGrok 4.5Optimus Alpha
Input price$2/M tokens—
Output price$6/M tokens—
Context window500K tokens1.0M tokens
WeightsClosed—
Free API (OpenRouter)No—
ReleasedJul 2026Apr 2025
At 10M a month$20.00$20.00–not listed
1M10M100M1B10M tokens

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

Where to run it1 host
Grok 4.51 host
HostInOutContextUptime
  • xAI$2.00 in·$6.00 out·500k·99.6% up
Optimus Alpha

No hosts listed on OpenRouter.

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

Common questions

What is the difference between Grok 4.5 and Optimus Alpha?

Grok 4.5 is developed by xAI while Optimus Alpha is developed by OpenRouter. Grok 4.5 has a 500K token context window vs Optimus Alpha's 1.0M. You can compare their actual outputs across 17 challenges on Rival to see how they differ in practice.

Which is better, Grok 4.5 or Optimus Alpha?

It depends on your use case. Grok 4.5 and Optimus Alpha each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 17 challenges so you can judge which fits your needs best.

How can I compare Grok 4.5 and Optimus Alpha on Rival?

This page shows a side-by-side comparison of Grok 4.5 and Optimus Alpha 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

  • Grok 4.5 vs Grok 4.6Version compare
  • Grok 4.5 vs Grok 4.7Same lab
  • Optimus Alpha vs Ox AlphaSame lab
  • Optimus Alpha vs OpenRouter Fusion · Budget (Jun 2026)Same lab
  • Optimus Alpha vs Gemma 4 26B A4BSame size
  • Optimus Alpha vs Gemma 4 31BNew provider
  • Grok 4.5 vs GLM 4 32BSame size
  • Grok 4.5 vs GLM 4.5Same size

Model pages

  • Grok 4.558 outputs, specs and price
  • Optimus Alpha19 outputs, specs and price
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