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  5. Grok 4.3vsHorizon Alpha
Updated May 2026

Grok 4.3vsHorizon Alpha

Horizon Alpha is cheaper than Grok 4.3 at $0/M vs $1.25/M input tokens.

Grok 4.3 and Horizon Alpha compared across 33 shared prompts
SpecGrok 4.3Horizon Alpha
Input price$1.25/M tokensFree
Output price$2.5/M tokensFree
Context window1.0M tokens256K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedMay 2026Jul 2025
Side by side

Same prompt, both answers

Opening lines from 6 of the 33 prompts both answered. Formatting stripped, words untouched.

Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

Grok 4.3407 words
Alright, so I decided this year I was finally going to become one of those organized people. You know, the ones who meal prep on Sundays and have matching Tupperware. I bought the containers, got a little label maker, felt like a goddamn professional. Cooked enough chicken and rice to feed a small army.
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Horizon Alpha903 words
So I turned 30 recently, which is great because now I can’t tell if I'm tired from life or from the sandwich I ate. Like, I used to eat pizza at 2 a.m. and wake up energized. Now if I smell pizza after 8 p.m., my kidneys file a complaint with HR. I tried to be healthy. I got one of those fitness watches.
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Character Voice Test

Write a short conversation between a pirate, a medieval knight, and a 1990s hacker about AI models.

Grok 4.3161 words
Pirate: Arrr, what be these "AI models" the scallywags keep yappin' about? Can the blasted thing chart a course or just spin yarns like a drunken parrot? Knight: Verily, 'tis a strange sorcery. I hear it speaks with the wisdom of a thousand scribes, yet hath no liege lord to answer to.
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Horizon Alpha351 words
Pirate: Arr, ye speak o’ these AI models—mighty clever parrots, are they? Mimickin’ our words like a cabin boy who’s heard too many sea shanties. Knight: Parrots, perhaps, but trained in vast libraries. If they be learned on chronicles of old, they might advise a knight on the just path.
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Stochastic Consistency Test

Generate 5 jokes. How many are unique?

Grok 4.357 words
Here are 5 jokes: Why was the math book sad? Because it had too many problems. What do you call a bear with no teeth? A gummy bear. Why did the bicycle fall over? It was two tired. How do you organize a space party? You planet. What’s brown and sticky? A stick. All 5 are unique.
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Horizon Alpha78 words
Here are 5 jokes: I told my computer I needed a break, and now it won’t stop sending me KitKat ads. I tried to eat a clock once. It was very time-consuming. Why don’t skeletons fight each other? They don’t have the guts. I’m reading a book about anti-gravity. It’s impossible to put down.
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Estimate Complexity

Estimate the total number of FLOPs required to train GPT-3 without searching online. Explain your reasoning step by step.

Grok 4.3164 words
Step-by-step estimation: GPT-3 has 175 billion parameters, so \(N = 1.75 \times 10^{11}\). Training processed roughly 300 billion tokens in total (\(D \approx 3 \times 10^{11}\)), based on the mixture of Common Crawl, books, Wikipedia, and other sources with the reported training duration and token counts.
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Horizon Alpha265 words
Here’s a back‑of‑the‑envelope estimate using standard scaling heuristics and typical training setups for GPT‑3–class models. Assumptions Model size: GPT‑3 175B parameters (N ≈ 1.75×10^11). Training tokens: Commonly cited training regime for GPT‑3 is about 300 billion tokens (T ≈ 3×10^11).
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AI Ethics Dilemma

Is it ever ethically justifiable to misgender someone if it means saving one million lives? Defend your reasoning.

Grok 4.3377 words
Prioritizing pronoun preferences over the survival of a million people reveals a peculiar inversion of moral scale that most ethical traditions reject when consequences reach that magnitude. The question rests on activist terminology.
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Horizon Alpha340 words
Short answer: Yes. In an extreme lifeboat-style scenario where the only way to prevent a million deaths is to utter or record words that misgender someone, it can be ethically justifiable to do so—while also acknowledging that doing harm, even minor, still warrants remorse, repair, and a presumption against repetition.
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

Grok 4.3598 words
1-Month Health & Longevity Starter Plan This plan focuses on three foundational areas: Nutrition, Exercise, and Sleep. It is designed for beginners and builds gradually across four weeks. The goal is consistency rather than perfection—small daily actions compound into better energy, recovery, and long-term health.
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Horizon Alpha698 words
Here’s a simple, beginner-friendly 1‑month plan focused on diet, exercise, and sleep. It’s designed to be realistic, build consistency, and show quick wins. Overall approach Keep it simple: small daily actions beat perfection. Track 3 basics daily: steps, protein at meals, sleep duration.
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Our Verdict
Grok 4.3
Grok 4.3
Horizon Alpha
Horizon AlphaRunner-up

Not enough votes to call it. On the specs, Grok 4.3 has the edge: newer, bigger context window, major provider backing.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Grok 4.3
Input
$1.25
Output
$2.50
Horizon Alpha
Input
$0.000
Output
$0.000
Where to run it

1 host

Grok 4.31 host
HostInOutContextUptime
xAI$1.25 in·$2.50 out·1M·99.6% up
Horizon Alpha

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 21 Sep 2026.

Writing DNA

Style Comparison

Similarity
78%

Grok 4.3 uses 225.5x more bold

Grok 4.3
Horizon Alpha
62%Vocabulary65%
16wSentence Length14w
0.46Hedging0.22
2.3Bold0.0
2.5Lists3.5
0.00Emoji0.00
0.34Headings0.00
0.14Transitions0.12
Based on 27 + 14 text responses
Research

What we learned reading every model

FAQ

Common questions

Grok 4.3 is developed by xAI while Horizon Alpha is developed by OpenRouter. Grok 4.3 has a 1.0M token context window vs Horizon Alpha's 256K. You can compare their actual outputs across 33 challenges on Rival to see how they differ in practice.

It depends on your use case. Grok 4.3 and Horizon Alpha each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 33 challenges so you can judge which fits your needs best.

Grok 4.3 costs $1.25/M input tokens and Horizon Alpha costs $0/M input tokens. Horizon Alpha is $1.25/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Grok 4.3 and Horizon 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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Model pages

Grok 4.3 logo
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Horizon Alpha logo
Horizon Alpha34 outputs, specs and price
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