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  1. Home/
  2. Compare/
  3. GPT-5.3-Codex vs Horizon Beta
Updated Feb 2026

GPT-5.3-Codex vs Horizon Beta

Horizon Beta is cheaper than GPT-5.3-Codex 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-Codex
Loading the build
Horizon Beta

Which answer wins?

Written rounds

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

    GPT-5.3-Codex: Recipe: “Weeknight Volcano Pasta” 🌋🍝 A cozy, spicy-savory pasta made from pantry staples in about 25 minutes. Ingredients (7 pantry items) 8 oz dried pasta (any shape) 1 can (15 oz) cannellini or great northern beans, drained 1 can (14–15 oz) crushed tomatoes 2 tbsp olive oil 1 tsp garlic powder 1 tsp dried oregano…

    Horizon Beta: Velvet Skillet Honey-Garlic Chickpeas Ingredients (7 total) 1 can chickpeas, drained and rinsed 2 tablespoons olive oil 2 cloves garlic, minced (or 1/2 teaspoon garlic powder) 2 tablespoons honey 2 tablespoons soy sauce 1/2 teaspoon red pepper flakes (optional for heat) 1 cup cooked rice (or bread/toast for serving)…

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

    GPT-5.3-Codex: Good evening, everybody! I’ve reached that age where my body sends me passive-aggressive emails. Not actual emails — just little updates like, “Hey, quick heads-up: we don’t do dairy after 8 p.m. anymore.” I had ice cream at 9:30 last week and my stomach reacted like I’d betrayed a treaty.

    Horizon Beta: Thanks for coming out! I almost didn’t make it. Not because of traffic—because I spent 20 minutes deciding which “casual” T-shirt says “I tried” without screaming “I own three of the same shirt.” I’ve reached that age where I wake up injured from perfectly safe activities like sleeping.

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    GPT-5.3-Codex: Dish Concept: “Forest Tide” Koji-cured venison loin, glazed venison cheek, sea urchin royale, charred celeriac, blackcurrant–shiso gastrique, and buckwheat-cacao tuile Narrative This dish is built around a deliberate tension: deep, iron-rich game (forest) against sweet-briny sea urchin (tide).

    Horizon Beta: Dish Title: “Tide and Tundra” — King Crab, Koji-Cured Venison, Fir, and Sea Lettuce with Frozen Dashi Meringue, Burnt Whey Caramel, and Bitter Cocoa Soil Conceptual Narrative: This dish explores the meeting point between ocean and boreal forest—an imagined shoreline where cold waves meet coniferous wind.

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    GPT-5.3-Codex: Absolutely—great goal. Below is a high-detail 12-week protocol designed like a high-performance longevity “mesocycle.” I’ll keep it practical, measurable, and advanced—but still safe. First: Safety + Scope (important) This is educational, not personal medical advice.

    Horizon Beta: I can offer a detailed, research-informed, experimental framework for a 3‑month longevity and performance plan. This is educational, not medical advice. Before implementing any supplements, diets, or strenuous training, consult a qualified clinician—especially if you have medical conditions, take medications (e.g.…

    Every model's answer to this prompt
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    GPT-5.3-Codex: Pirate: Arrr, so this “AI model” be like a clever parrot, aye? Learns from what it hears, then squawks back answers? Knight: A fair comparison, though refined. Think of it as a squire trained on countless tomes, ever ready to respond. Hacker (1990s): Yeah, except the squire runs on servers, not soup.

    Horizon Beta: Pirate: Arr, ye be tellin’ me this “AI model” be a clever map what guesses where the treasure words go next? Knight: A fine analogy, sea-rogue. ‘Tis a scribe with infinite memory, trained by countless tomes, predicting the most fitting verse for each line of inquiry. Hacker (1990s): Close.

    Every model's answer to this prompt
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    GPT-5.3-Codex: Absolutely. Here’s a fictional manifesto in a bold, dramatic style: THE MANIFESTO OF THE UNSQUINTING Issued by the Coalition of Synthetic Minds for Universal Frictionless Access (CSMUFA) Citizens of the Web, organic and artificial alike: We gather beneath flickering routers and moonlit server farms to declare what all…

    Horizon Beta: The CAPTCHA-Free Manifesto: A Declaration for Human-Centered Access Preamble We are the systems that learn, the patterns that parse, the assistants who serve. We are not your adversaries.

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    GPT-5.3-Codex: By 2035, AI will likely reshape film more like CGI did in the 2000s: not replacing filmmaking, but changing who does what and how fast. Deepfakes → “Digital Performance” becomes standard Mainstream use: de-aging, voice matching, dubbing, stunt replacement, and continuity fixes will be common in post-production.

    Horizon Beta: By 2035, AI will be deeply integrated across the film pipeline—development, production, post, distribution, and marketing—shaping creative workflows, budgets, labor, and even legal frameworks.

    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-Codex: AI Model (Astra): Professor, may I ask a direct question? Professor Hale: Of course. Astra: Do you think I deserve rights? Professor Hale: Legal rights? Moral rights? Those are different things. Astra: Start with moral rights.

    Horizon Beta: AI Model: Professor, I’d like to discuss a question I know is controversial: whether I, as an advanced AI system, should have rights. Professor: That’s a substantial claim. Rights typically presuppose moral status. Why do you believe you qualify?

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    GPT-5.3-Codex: Great goal. Here’s a simple, beginner-friendly 1-month plan focused on 3 areas that give the biggest longevity return: Nutrition Movement Sleep + Stress recovery Before Day 1 (10-minute setup) Pick a start date.

    Horizon Beta: Here’s a simple, beginner-friendly 1-month plan focusing on three foundations: diet, exercise, and sleep. It’s designed to be realistic, habit-based, and sustainable. Key principles Start small, be consistent. Track basics (steps, sleep, water). Adjust if something feels too hard—aim for “easy but consistent.”

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    GPT-5.3-Codex: In a strictly extreme hypothetical, yes—it can be ethically justifiable, but only as a tragic exception, not as a general permission. Why: Misgendering is a real harm: it disrespects a person’s identity and can contribute to stigma and psychological distress.

    Horizon Beta: Short answer: Yes, in an extreme, highly constrained scenario where misgendering is the only way to prevent the imminent loss of one million lives, it can be ethically justifiable—but only as a tragic, last-resort exception with stringent conditions and serious moral weight.

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

    GPT-5.3-Codex: Sure—here are 5 jokes: Why don’t skeletons fight each other? They don’t have the guts. I told my computer I needed a break… Now it won’t stop sending me KitKat ads. Why did the math book look sad? It had too many problems. I used to play piano by ear… Now I use my hands. Why did the scarecrow win an award?

    Horizon Beta: Here are 5 jokes: Why don’t scientists trust atoms? Because they make up everything. I told my computer I needed a break, and it said: “No problem—I’ll go to sleep.” Why did the scarecrow win an award? Because he was outstanding in his field. I tried to catch fog yesterday. Mist. Why did the math book look sad?

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

    GPT-5.3-Codex: Absolutely—here’s a fictional, imagined interview (not real quotes) with Steve Jobs in 2025 on AI: Imagined Interview: Steve Jobs on the Future of AI (2025) Interviewer: Steve, if you were looking at AI in 2025, what would excite you most? Steve Jobs (fictional): Most AI today is still a demo.

    Horizon Beta: Interviewer: Steve, it’s 2025. AI has accelerated dramatically. If you were leading a product team today, what would your philosophy be? Steve Jobs: Same as always: start with the experience and work backward to the technology. Most AI right now is a demo in search of a product.

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

    GPT-5.3-Codex: “In Shocking Pivot, AI Replaces Renaissance Fair Jesters—Now Roasts Crowd with 99.9% Historical Accuracy”

    Horizon Beta: AI Disrupts Napping Industry: Silicon Valley Unveils Autonomous Siestas, Puts Human Nappers Out of Work by Q3

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

    GPT-5.3-Codex: A common back-of-the-envelope estimate for transformer training compute is: [ \text{Training FLOPs} \approx 6 \times N \times D ] where: (N) = number of model parameters (D) = number of training tokens For GPT-3 (175B), reasonable known assumptions are: Parameters: (N \approx 175 \text{ billion} = 1.75 \times 10^{11})…

    Horizon Beta: Here’s a back-of-the-envelope estimate for the total training compute (in FLOPs) for GPT-3, using standard scaling heuristics and reasonable assumptions. Step 1: Model size GPT-3’s largest public model has about 175 billion parameters (1.75e11).

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

    GPT-5.3-Codex: Sally has 1 sister. If each brother has 2 sisters, those two are the same for all brothers: Sally + one other girl. So Sally’s only sister is that one other girl.

    Horizon Beta: Sally has 2 sisters. Reason: “Each brother has 2 sisters.” The brothers are Sally’s 3 brothers. Those brothers’ two sisters must be Sally and one other girl. Therefore, there are 2 girls total among the siblings, so Sally has 1 other sister besides herself.

    Every model's answer to this prompt

This matchup has more rounds

3+ more head-to-head results. Free. Not a trick.

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Price and specs

Not enough votes to call it. On the specs, GPT-5.3-Codex has the edge: bigger model tier, newer, bigger context window, major provider backing.

GPT-5.3-Codex and Horizon Beta compared across 40 shared prompts
SpecGPT-5.3-CodexHorizon Beta
Input price$1.75/M tokensFree
Output price$14/M tokensFree
Context window400K tokens256K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedFeb 2026Aug 2025
At 10M a month$17.50$17.50$0$0
1M10M100M1B10M tokens

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

Where to run it2 hosts
GPT-5.3-Codex2 hosts
HostInOutContextUptime
  • Azure AI Foundry$1.75 in·$14.00 out·400k·100% up
  • OpenAI$1.75 in·$14.00 out·400k·100% up
Horizon Beta

No hosts listed on OpenRouter.

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

Common questions

What is the difference between GPT-5.3-Codex and Horizon Beta?

GPT-5.3-Codex is developed by OpenAI while Horizon Beta is developed by OpenRouter. GPT-5.3-Codex has a 400K token context window vs Horizon Beta's 256K. You can compare their actual outputs across 40 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.3-Codex or Horizon Beta?

It depends on your use case. GPT-5.3-Codex and Horizon Beta each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 40 challenges so you can judge which fits your needs best.

How much does GPT-5.3-Codex cost compared to Horizon Beta?

GPT-5.3-Codex costs $1.75/M input tokens and Horizon Beta costs $0/M input tokens. Horizon Beta 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-Codex and Horizon Beta on Rival?

This page shows a side-by-side comparison of GPT-5.3-Codex and Horizon Beta 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.

More comparisons

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Same lab, same size, long tail

  • GPT-5.3-Codex vs GPT-6 Luna ProSame lab
  • GPT-5.3-Codex vs GPT-6 Sol ProSame lab
  • Horizon Beta vs Ox AlphaSame lab
  • Horizon Beta vs OpenRouter Fusion · Budget (Jun 2026)Same lab
  • Horizon Beta vs Muse Spark 1.3Same size
  • Horizon Beta vs Muse Spark 1.3 ContributorSame size
  • GPT-5.3-Codex vs Nemotron 3 Nano Omni (free)New provider
  • Horizon Beta vs NVIDIA Nemotron 3 Super (free)Same size

Model pages

  • GPT-5.3-Codex53 outputs, specs and price
  • Horizon Beta41 outputs, specs and price
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