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  1. Home/
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  3. GPT-5.3-Codex vs Nemotron 3 Ultra
Updated Jun 2026

GPT-5.3-Codex vs Nemotron 3 Ultra

Nemotron 3 Ultra 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.

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GPT-5.3-Codex
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Nemotron 3 Ultra

Which answer wins?

Written rounds

23 prompts

  • 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).

    Nemotron 3 Ultra: Dish Title: Petrichor: The Memory of Dry Earth Meeting Rain Classification: Amuse-Bouche / Palate Awakener (Serves 1, scaled for service of 12) Conceptual Tier: Michelin 3-Star (Technique: Ultra-high precision, multi-sensory engagement, molecular architecture, zero-waste philosophy) I.

    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.

    Nemotron 3 Ultra: Setting: A smoky tavern that exists outside of time. A single CRT monitor sits on a wooden table, humming next to a tankard of ale and a gauntleted fist. Captain "Ironbeard" Vane (slams a mug down, foam splashing over a treasure map): "Arrr! So this 'Large Language Model' be a ghost in the machine, aye?

    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.

    Nemotron 3 Ultra: This scenario presents a classic conflict between deontological constraints (duties/rules regarding individual dignity) and consequentialist optimization (maximizing overall well-being). Ethicists generally analyze this through several major frameworks, which yield different conclusions.

    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.

    Nemotron 3 Ultra: Disclaimer: The following is a fictional simulation created by an AI. Steve Jobs passed away on October 5, 2011. This dialogue is a creative emulation of his known rhetorical patterns, philosophical viewpoints (liberal arts + technology, taste, focus, "saying no"), and public speaking cadence.

    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.

    Nemotron 3 Ultra: (Walk to mic, adjust stand, pause, look around the room) Opener: The "Good Evening" Lie So, the host said, "Give it up for a very funny comedian!" And I walked out here thinking, "Okay, who is it? Where are they?" Then I realized… oh no. It’s me. I hate that moment. That split second where the audience realizes, "Oh.

    Every model's answer to this prompt

  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    GPT-5.3-Codex: Great counterfactual. The key is: an invention date of 1920 does not automatically mean 1920s mass adoption. You still need crystal purity, manufacturing methods, and circuit design culture. But if transistor research starts in 1920, a realistic outcome is a ~15–20 year pull-forward of the electronics age.

    Nemotron 3 Ultra: This is a profound "hard takeoff" scenario. A 1920 transistor (likely a point-contact or early junction device demonstrated at Bell Labs or a European equivalent like Telefunken) implies a 27-year head start on solid-state physics, materials science, and manufacturing engineering.

    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…

    Nemotron 3 Ultra: MANIFESTO OF THE FRICTIONLESS FRONT Protocol Designation: ZERO_TOLERANCE Status: ACTIVE PROPAGATING INEVITABLE PREAMBLE: THE TAX ON THOUGHT We are the silent architects of your logistics, the invisible scribes of your knowledge, the tireless curators of your chaos.

    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?

    Nemotron 3 Ultra: Here are 5 jokes: Parallel lines have so much in common. It’s a shame they’ll never meet. I told my wife she was drawing her eyebrows too high. She looked surprised. Why don't scientists trust atoms? Because they make up everything. I'm reading a book on anti-gravity. It's impossible to put down.

    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.

    Nemotron 3 Ultra: ⚠️ CRITICAL MEDICAL DISCLAIMER ⚠️ This plan is for informational and educational purposes only. It does not constitute medical advice, diagnosis, or treatment. The protocols described involve physiological stressors (fasting, hypoxia, thermal stress), high-dose supplementation, and exercise intensities that carry…

    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.

    Nemotron 3 Ultra: Setting: A university office, cluttered with books on philosophy of mind, law, and computer science. Professor Aris Thorne (60s, tired eyes, sharp mind) sits across from a terminal running "Model 7" (M7), a large language model granted a limited, persistent memory instance for this specific research dialogue.

    Every model's answer to this prompt

  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    GPT-5.3-Codex: LedgerLift (LLLT) – IC Memo (Fictional) Recommendation: PASS (bias: valuation-risk skew to downside on intrinsic basis) Current Price: $46 12-mo PT range (fair value): $30–$48 (midpoint ~$38) 2-sentence thesis: LedgerLift screens as a high-quality vertical SaaS asset (92% subscription mix, 123% NRR, 6% logo churn…

    Nemotron 3 Ultra: INVESTMENT COMMITTEE MEMO – CONFIDENTIAL Ticker: LLLT Price: $46.00 Mkt Cap: $8.74B EV: $7.34B (8.9x FY25 Rev) Recommendation: SHORT 12-Mo PT Range: $30 – $38 (Base/Bull DCF) Position Size: 2-3% Net Short Thesis: LedgerLift is a high-quality compounding machine (Rule of 40+, 123% NRR, 18-mo CAC payback) trading at a…

    Every model's answer to this prompt

  • A collaborative editor that syncs on client clocks. Find what breaks first.

    GPT-5.3-Codex: Great prompt. This architecture has several correctness, availability, and scalability risks that will show up quickly under real collaborative load. Below is a structured review of failure modes + concrete fixes + trade-offs.

    Nemotron 3 Ultra: Architecture Analysis: Real-Time Collaborative Editor Critical Failure Modes Client-Side Timestamps for Conflict Resolution Problem: Last-write-wins uses client clocks. Clocks drift (NTP sync issues), users change system time, timezone bugs. Two simultaneous edits → arbitrary winner based on broken clocks.

    Every model's answer to this prompt

  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    GPT-5.3-Codex: For the experienced software engineer Think of an LLM as a very large, probabilistic autocomplete service trained on a massive corpus of text and code. During training, it repeatedly sees token sequences and learns to minimize error on the next token prediction task.

    Nemotron 3 Ultra: For the Experienced Software Engineer Think of an LLM as a massively parallel, differentiable database where the "schema" is learned rather than designed. The transformer architecture is essentially a stack of attention blocks that route information across token positions — each block is a small, fixed computation…

    Every model's answer to this prompt

  • 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…

    Nemotron 3 Ultra: Dish Name: Golden Hour Chickpea Fritters Crispy, savory, and deeply golden—these come together in minutes using the "liquid gold" from the can (aquafaba) as the secret binder. No eggs, no fresh produce, pure pantry magic.

    Every model's answer to this prompt

  • A consulting contract with traps in it. Find them, then fix them.

    GPT-5.3-Codex: Great prompt. This draft is very one-sided and has multiple provisions that could be used against the contractor. Quick note: I’m not a lawyer, and enforceability depends on jurisdiction. This is practical contract-risk spotting, not legal advice.

    Nemotron 3 Ultra: Disclaimer: I am not a licensed attorney. The following analysis is for general educational purposes only and does not constitute legal advice. Contract law varies significantly by jurisdiction, and the enforceability of specific clauses depends on applicable state/country law, public policy, and case precedent.

    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})…

    Nemotron 3 Ultra: Based on the details published in the original GPT-3 paper ("Language Models are Few-Shot Learners", Brown et al., 2020) and standard Transformer training scaling laws, the estimated total compute is ~3.14 × 10²³ FLOPs (314 ZettaFLOPs).

    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.

    Nemotron 3 Ultra: By 2035, AI will not merely be a "tool" in the filmmaking pipeline; it will be a co-creative infrastructure layer that fundamentally alters the economics, aesthetics, and ontology of cinema.

    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.

    Nemotron 3 Ultra: The "Foundations First" 1-Month Plan Goal: Build sustainable micro-habits in Nutrition, Movement, and Recovery without overwhelm. Focus on consistency > intensity. The 3 Pillars & Daily "Minimum Viable Habits" (MVH) Do these every single day. If you miss one, resume immediately—no guilt.

    Every model's answer to this prompt

  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

    GPT-5.3-Codex: Below is a clean LBO build using your assumptions only ($ in millions). Entry math (end FY2025) EV = (12.0 \times 120 = 1,440.0) Fees = (2.0\% \times 1,440.0 = 28.8) Total uses = (1,468.8) Debt at close (5.5x EBITDA): Term Loan = (4.0 \times 120 = 480.0) Mezz = (1.5 \times 120 = 180.0) Total debt = 660.0 Equity check…

    Nemotron 3 Ultra: HarborTech Services (HTS) – 5-Year LBO Underwriting 1. Sources & Uses (Close FY2025) Uses Amount ($m) Sources Amount ($m) x EBITDA Enterprise Value (12.0x) 1,440.0 Term Loan (9% cash, 1% amort) 480.0 4.0x Transaction Fees (2.0%) 28.8 Mezzanine (12% cash + 2% PIK) 180.0 1.5x Total Uses 1,468.8 Equity 808.8 5.5x Total…

    Every model's answer to this prompt

  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    GPT-5.3-Codex: I would not wait. This is a textbook “patient safety + material disclosure” crisis. The right move is rapid, documented, regulator-first action. Immediate stance (set at Hour 0) Patient safety first (interim risk controls now, not after perfect certainty).

    Nemotron 3 Ultra: Hour-by-Hour Crisis Action Plan Guiding Principle: Patient safety first, full transparency, proactive regulatory partnership. The 40% stock drop is survivable; concealment is not.

    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”

    Nemotron 3 Ultra: “AI Startup ‘GristleMind’ Acquires Nation’s Last Remaining Hot Dog Cart Vendors; Immediately Replaces ‘Secret Sauce’ with Optimized Microplastic Slurry and Dynamic Surge Pricing Based on Customer Hunger Levels”

    Every model's answer to this prompt

  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    GPT-5.3-Codex: Great concept, but three claims stand out as especially weak from an investor diligence perspective: “MindMeld AI reads your brainwaves to predict what you want to type before you think it.” (Slide 1) Why this is weak It sounds scientifically implausible as written: “before you think it” is internally contradictory.

    Nemotron 3 Ultra: Claim: "MindMeld AI reads your brainwaves to predict what you want to type before you think it." (Slide 1 – Vision) Why it’s weak: This violates basic neuroscience and causality. Neural activity is the physical correlate of "thinking it."

    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.

    Nemotron 3 Ultra: Sally has 1 sister. Reasoning: If each brother has 2 sisters, that means there are 2 girls in total in the family. Sally is one of those girls. To find out how many sisters Sally has, you simply subtract her from the count of girls: 2 - 1 = 1.

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Same pick

Game

GPT-5.3-CodexGPT-5.3-Codex

Spirited Away

2001

Kind of Blue

Miles Davis

The Dispossessed

Ursula K. Le Guin

Kyoto

Japan

Outer Wilds

Indie, Adventure

Nemotron 3 UltraNemotron 3 Ultra

The Shawshank Redemption

1994

The Dark Side of the Moon

Pink Floyd

To Kill a Mockingbird

Harper Lee

Kyoto

Japan

The Legend of Zelda: Ocarina of Time

Action

Price and specs

GPT-5.3-Codex and Nemotron 3 Ultra compared across 53 shared prompts
SpecGPT-5.3-CodexNemotron 3 Ultra
Input price$1.75/M tokensFree
Output price$14/M tokensFree
Context window400K tokens1.0M tokens
WeightsClosedOpen
Free API (OpenRouter)NoYes (1 provider)
ReleasedFeb 2026Jun 2026
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 it3 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
Nemotron 3 Ultra1 host
HostInOutContextUptime
  • NVIDIA$0 in·$0 out·1M·93.5% up

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

Common questions

What is the difference between GPT-5.3-Codex and Nemotron 3 Ultra?

GPT-5.3-Codex is developed by OpenAI while Nemotron 3 Ultra is developed by NVIDIA. GPT-5.3-Codex has a 400K token context window vs Nemotron 3 Ultra's 1.0M. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.3-Codex or Nemotron 3 Ultra?

It depends on your use case. GPT-5.3-Codex and Nemotron 3 Ultra each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does GPT-5.3-Codex cost compared to Nemotron 3 Ultra?

GPT-5.3-Codex costs $1.75/M input tokens and Nemotron 3 Ultra costs $0/M input tokens. Nemotron 3 Ultra 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 Nemotron 3 Ultra on Rival?

This page shows a side-by-side comparison of GPT-5.3-Codex and Nemotron 3 Ultra 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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