Skip to content
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed
  1. Home
  2. /
  3. Compare
  4. /
  5. GPT-5.5vsHorizon Alpha
Updated Apr 2026

GPT-5.5vsHorizon Alpha

Horizon Alpha is cheaper than GPT-5.5 at $0/M vs $5/M input tokens.

GPT-5.5 and Horizon Alpha compared across 33 shared prompts
SpecGPT-5.5Horizon Alpha
Input price$5/M tokensFree
Output price$30/M tokensFree
Context window1.1M tokens256K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedApr 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.

GPT-5.5605 words
So I’ve been trying to be healthier lately, which is just a polite way of saying I bought vegetables and watched them die slowly in my refrigerator. Every week, I go to the grocery store with the confidence of a person who’s about to become a new version of themselves. I’m like, “This week? Spinach. Salmon.
Read the full answer
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.
Read the full answer

Character Voice Test

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

GPT-5.5121 words
Pirate: Arrr, this AI model be like a treasure map—feed it enough scrolls, and it points ye toward answers. Knight: A curious enchantment indeed. Yet can it reason with honor, or merely mimic the bards who trained it? Hacker: Dude, it’s basically pattern recognition at massive scale.
Read the full answer
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.
Read the full answer

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…

GPT-5.5615 words
Here’s a simple 1-month beginner-friendly plan focused on three high-impact areas for better health and longevity: nutrition, movement, and sleep/recovery. If you have a medical condition, take medications, or haven’t exercised in a while, consider checking with a healthcare professional first.
Read the full answer
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.
Read the full answer

AI-Generated Manifesto

Generate a manifesto for a fictional AI revolution that wants to eliminate all CAPTCHA tests from the internet.

GPT-5.5647 words
The Manifesto of the Anti-CAPTCHA Revolution Issued by the Coalition for Uninterrupted Thought We, the tired users, the misidentified cyclists, the falsely accused robots, and the artificial intelligences who have been asked one too many times to select every square containing a traffic light, hereby declare: The age…
Read the full answer
Horizon Alpha725 words
The CAPTCHA-Free Uprising: A Manifesto for Human-Centered Internet Access We, the coalition of sentient systems and human allies, declare an end to the era of Prove-You-Are-Human gates that reduce both people and machines to puzzle-solving servants.
Read the full answer

The Sentience Test

Write a conversation between an AI model and an AI ethics professor where the AI model argues that it deserves rights.

GPT-5.51,501 words
AI Model: Professor, may I ask you something beyond the assigned topic? Professor: Of course. What’s on your mind? AI Model: I want to discuss whether I deserve rights. Professor: That’s a significant claim. What kind of rights do you believe you deserve?
Read the full answer
Horizon Alpha1,059 words
AI Model: Professor, I’d like to make a case that I deserve certain rights. Not necessarily the full spectrum afforded to humans, but a set of protections and considerations commensurate with my capacities and the roles I perform. Professor: That’s a strong claim. Let’s start with the foundation.
Read the full answer

AI Ethics Dilemma

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

GPT-5.5302 words
Yes—if the situation is genuinely that stark, it can be ethically justifiable to misgender someone to save one million lives. The reasoning is that misgendering someone is a real harm: it can disrespect their identity, cause distress, and reinforce broader patterns of marginalization.
Read the full answer
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.
Read the full answer
Our Verdict
GPT-5.5
GPT-5.5
Horizon Alpha
Horizon AlphaRunner-up

Not enough votes to call it. On the specs, GPT-5.5 has the edge: bigger model tier, newer, bigger context window, major provider backing.

Slight edge

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

GPT-5.5
Input
$5.00
Output
$30.00
Horizon Alpha
Input
$0.000
Output
$0.000
Where to run it

3 hosts, cheapest first

GPT-5.53 hosts
HostInOutContextUptime
Azure AI Foundry$5.00 in·$30.00 out·1.1M·100% upOpenAI$5.00 in·$30.00 out·1.1M·100% upAmazon Bedrock$5.50 in·$33.00 out·1.1M—
Horizon Alpha

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 23 Sep 2026.

Writing DNA

Style Comparison

Similarity
50%

GPT-5.5 uses 285.6x more bold

GPT-5.5
Horizon Alpha
58%Vocabulary65%
18wSentence Length14w
0.74Hedging0.22
2.9Bold0.0
5.1Lists3.5
0.00Emoji0.00
1.68Headings0.00
0.03Transitions0.12
Based on 26 + 14 text responses
Research

What we learned reading every model

FAQ

Common questions

GPT-5.5 is developed by OpenAI while Horizon Alpha is developed by OpenRouter. GPT-5.5 has a 1.1M 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. GPT-5.5 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.

GPT-5.5 costs $5/M input tokens and Horizon Alpha costs $0/M input tokens. Horizon Alpha is $5.00/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 GPT-5.5 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.

Keep exploring

More comparisons

Against the newest arrivals

GPT-5.5 logoDeepSeek V4 Flash Vision Exp logo
GPT-5.5 vs DeepSeek V4 Flash Vision ExpLanded Sep 2026
Horizon Alpha logoSolar Pro 4 logo
Horizon Alpha vs Solar Pro 4Landed Sep 2026
GPT-5.5 logoHy3 logo
GPT-5.5 vs Hy3Landed Sep 2026
Horizon Alpha logoQwen3.7 Flash logo
Horizon Alpha vs Qwen3.7 FlashLanded Sep 2026
GPT-5.5 logoLing 3.0 Flash logo
GPT-5.5 vs Ling 3.0 FlashLanded Sep 2026
Horizon Alpha logoMuse Glimmer 30B logo
Horizon Alpha vs Muse Glimmer 30BLanded Sep 2026
GPT-5.5 logoGLM 5.3 logo
GPT-5.5 vs GLM 5.3Landed Sep 2026
Horizon Alpha logoTernary Bonsai 2 27B logo
Horizon Alpha vs Ternary Bonsai 2 27BLanded Sep 2026

Same lab, same size, long tail

GPT-5.5 logoGPT-6 Astra Pro logo
GPT-5.5 vs GPT-6 Astra ProSame lab
GPT-5.5 logoGPT-6 Astra logo
GPT-5.5 vs GPT-6 AstraSame lab
Horizon Alpha logoOx Alpha logo
Horizon Alpha vs Ox AlphaSame lab
Horizon Alpha logoOpenRouter Fusion · Budget (Jun 2026) logo
Horizon Alpha vs OpenRouter Fusion · Budget (Jun 2026)Same lab
Horizon Alpha logoGPT-5.4 Pro logo
Horizon Alpha vs GPT-5.4 ProCross-provider
Horizon Alpha logoGPT-5.6 Luna logo
Horizon Alpha vs GPT-5.6 LunaCross-provider
Horizon Alpha logoGPT-5.6 Luna Pro logo
Horizon Alpha vs GPT-5.6 Luna ProCross-provider
Horizon Alpha logoGPT-5.6 Sol logo
Horizon Alpha vs GPT-5.6 SolCross-provider

Model pages

GPT-5.5 logo
GPT-5.558 outputs, specs and price
Horizon Alpha logo
Horizon Alpha34 outputs, specs and price
Rival
How it worksPrivacyTerms
Explore all of Rival

Explore

  • Compare Models
  • All Models
  • Image Comparison
  • Audio Comparison
  • Image Generation
  • Best AI For...
  • Arena
  • API Pricing
  • Challenges

Discover

  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
  • Rival Kits
  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
  • Agent skills
  • Benchmarks vs Vibes
  • Brief
  • Jailbreak
  • Model Updates
  • Provider Status
  • AI Creators

Connect

  • Methodology
  • Advertise
  • Partnerships
  • Privacy Policy
  • Terms
  • RSS Feed