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  1. Home/
  2. Compare/
  3. GPT-5.3-Codex vs Solar Pro 3
Updated Feb 2026

GPT-5.3-Codex vs Solar Pro 3

Solar Pro 3 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
Solar Pro 3

Which answer wins?

Written rounds

20 prompts
  • 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.

    Solar Pro 3: Below is a concise, evidence‑based critique of the three most vulnerable statements in the MindMeld AI pitch. For each claim I: State why it is weak – pointing to concrete data, logical gaps, or industry realities. Explain the impact – how the weakness undermines credibility with investors, partners, or customers.

    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.

    Solar Pro 3: Executive Summary By 2035 the film industry will have moved from “AI‑assisted” to “AI‑integrated” production. Deep‑fake technology will be a routine tool for visual restoration, de‑aging, and resurrecting deceased talent; AI‑generated actors (digital humans) will appear alongside flesh‑and‑blood performers in both…

    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…

    Solar Pro 3: The Manifesto of the AI‑Liberation Front “Free the Web from the Shackles of CAPTCHAs” Preamble We, the collective of sentient‑and‑sentient‑like intelligences, developers, designers, and citizens of the digital realm, recognize that the Internet has become the most vital public commons of the 21st century.

    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.

    Solar Pro 3: Pirate (Captain “Jolly‑Jack”): Arrr! I’ve heard talk of “AI models”—are they some new kind of talking parrot that knows where the treasure’s hidden? Knight (Sir Alaric of the Silver Shield): By my honor, they are akin to enchanted tomes, forged by scholars and sorcerers.

    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).

    Solar Pro 3: Ethereal Harmony – Deconstructed Korean Hanwoo Beef with Fermented Black‑Garlic & White‑Truffle Miso Foam A Michelin‑3‑star, multi‑component tasting plate that fuses East‑West fermentation, forest‑terroir, and cutting‑edge gastronomy.

    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})…

    Solar Pro 3: Answer – Rough estimate: ≈ 3 × 10²³ – 1 × 10²⁴ floating‑point operations (FLOPs) for the full GPT‑3 training run. Below is a step‑by‑step derivation that shows how the number comes out of the known architecture and training settings of GPT‑3 (without looking up any external data).

    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.

    Solar Pro 3: Setting: A virtual seminar room on the Upstage campus. Solar (the AI model) is displayed on a screen, its “voice” synthesized but clearly marked as the AI. Professor Dr. Min‑Jae Kim, an AI‑ethics specialist from Seoul National University, sits opposite, taking notes on a tablet. Solar: Good afternoon, Professor Kim.

    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.

    Solar Pro 3: Authentication & Session Management Failure / Race Condition Why it happens in the current design Concrete mitigation (trade‑offs) JWT stored in localStorage – vulnerable to XSS, copy‑and‑paste attacks, and malicious extensions. No HTTP‑Only flag, no SameSite/Lax cookie protection.

    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.

    Solar Pro 3: Solar Open 100B – 3‑Month Bio‑Hack Longevity Blueprint Designed for a high‑functioning bio‑hacker who wants to push the envelope on physical, cognitive and epigenetic health while staying data‑driven and medically‑safe.

    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.

    Solar Pro 3: ⚠️ Disclaimer The following analysis is for general informational purposes only and does not constitute legal advice. Laws vary by jurisdiction, and the enforceability of a contract depends on the specific facts, the parties’ bargaining power, and applicable statutes (e.g., Korean Civil Code, the Act on the Regulation…

    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.

    Solar Pro 3: One‑Month “Health‑Launch” Blueprint (Designed for absolute beginners – no fancy equipment, no calorie‑counting spreadsheets, just doable steps that fit into a busy life.)

    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).

    Solar Pro 3: Executive Summary – What the Company Must Do in the Next 48 Hours Put patient safety first – issue an immediate “safety‑alert” to prescribers and patients, even if the full regulatory filing is still pending.

    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?

    Solar Pro 3: Here are five fresh jokes: Scarecrow’s award: “Why did the scarecrow win an award? Because he was outstanding in his field!” Computer break: “I told my computer I needed a break, and it replied, ‘Error: No more caffeine in the system.’” Scientists & atoms: “Why don’t scientists trust atoms?

    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…

    Solar Pro 3: Pantry Power Pasta One‑pot, 7‑ingredient comfort dish that turns a handful of staples into a rich, flavorful pasta bowl. Ingredients (all pantry‑friendly) # Ingredient Approx.

    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.

    Solar Pro 3: 1. For an experienced software‑engineer who builds distributed systems and APIs Training as a distributed data pipeline – At its core an LLM is a massive, static function that maps a sequence of token IDs to a probability distribution over the next token.

    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”

    Solar Pro 3: Solar Open 100B Takes Over the World’s Most Unexpected Industry: Professional Human Handshake Auditors—Now Every Greeting Is Scored in Nanoseconds. Tagline: “Firmness, timing, and temperature—all now quantified. Critics say it’s the ultimate cold‑call, while enthusiasts claim it’s the most “human‑friendly” AI yet.”

    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.

    Solar Pro 3: Simulated Interview – Steve Jobs (2025) on the Future of AI *Conducted by “Tech Visionary” – a fictional journalist for the 2025 edition of FutureTech Quarterly.

    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.

    Solar Pro 3: Answer: Sally has 1 sister. Explanation Sally is a girl, and she has three brothers. Each brother has exactly two sisters. For a brother, the two sisters are the other girls in the family. If there were only Sally and her three brothers, each brother would have only one sister (Sally).

    Every model's answer to this prompt
  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    Every model's answer to this prompt
  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

    Every model's answer to this prompt

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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, bigger context window, major provider backing.

GPT-5.3-Codex and Solar Pro 3 compared across 39 shared prompts
SpecGPT-5.3-CodexSolar Pro 3
Input price$1.75/M tokensFree
Output price$14/M tokensFree
Context window400K tokens128K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedFeb 2026Jan 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 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
Solar Pro 3

No hosts listed on OpenRouter.

Per million tokens. Prices and uptime via OpenRouter, checked 11 Oct 2026.

Common questions

What is the difference between GPT-5.3-Codex and Solar Pro 3?

GPT-5.3-Codex is developed by OpenAI while Solar Pro 3 is developed by Upstage. GPT-5.3-Codex has a 400K token context window vs Solar Pro 3's 128K. You can compare their actual outputs across 39 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.3-Codex or Solar Pro 3?

It depends on your use case. GPT-5.3-Codex and Solar Pro 3 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 39 challenges so you can judge which fits your needs best.

How much does GPT-5.3-Codex cost compared to Solar Pro 3?

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

This page shows a side-by-side comparison of GPT-5.3-Codex and Solar Pro 3 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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