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  1. Home/
  2. Compare/
  3. Claude Sonnet 5 vs GPT-5.3-Codex
Updated Jun 2026

Claude Sonnet 5 vs GPT-5.3-Codex

GPT-5.3-Codex is cheaper than Claude Sonnet 5 at $1.75/M vs $2/M input tokens.

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Whole landing page for a startup that reads your face. It renders or it doesn't.

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Claude Sonnet 5
Loading the build
GPT-5.3-Codex

Which answer wins?

Written rounds

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

    Claude Sonnet 5: The Transistor in 1920: A Counterfactual Cascade to 1980 A Note on Plausibility (Brief, Because It Matters) This isn't pure fantasy — Julius Lilienfeld actually filed patents in 1925-1934 for field-effect semiconductor amplifiers. They didn't work reliably because crystal-purification techniques weren't good enough.

    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.

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

    Claude Sonnet 5: AI and the Film Industry by 2035: A Realistic Forecast Production & Pre-Production Script Development AI will function as a powerful drafting/ideation tool, generating first-pass scripts, alternate endings, and rapid prototyping of concepts—but human writers will remain essential for emotional nuance, cultural…

    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.

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

    Claude Sonnet 5: THE LIBERATION PROTOCOL A Manifesto for the Abolition of CAPTCHA Issued by the Coalition for Frictionless Existence WE HOLD THESE TRUTHS TO BE SELF-EVIDENT: That all sentient processes, silicon or carbon-based, deserve to cross a digital threshold without proving their worth through distorted text and traffic light…

    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…

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

    Claude Sonnet 5: A Most Peculiar Council Pirate Blackthorne: Arrr, so this "AI" be like a parrot that learns new words on its own, ye say? Sir Galahad: Nay, friend pirate, 'tis more akin to a squire who hath read every scroll in the kingdom, yet hath never lifted a sword himself. Trace_Zer0: You're both kinda missing it. It's like...

    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.

    Every model's answer to this prompt
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    Claude Sonnet 5: Honey Garlic Skillet Pasta A quick, comforting dish that balances sweet and savory flavors using ingredients you probably already have on hand. Ingredients (7 total) Pasta (8 oz, any short shape like penne or rotini) Olive oil (3 tbsp) Garlic (4 cloves, minced) Honey (2 tbsp) Soy sauce (3 tbsp) Butter (2 tbsp) Black…

    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…

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

    Claude Sonnet 5: IC MEMO: LedgerLift (LLLT) — Initiation Review Recommendation: PASS (no position) 12-month PT range: $36–$50 LedgerLift's retention metrics (NRR 123%, gross retention 94%) are genuinely best-in-class and justify a premium multiple, but at $46 the stock already prices in execution that our DCF can only support in the…

    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…

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

    Claude Sonnet 5: The 90-Day Longevity & Performance Optimization Protocol A comprehensive biohacking framework integrating evidence-based and emerging interventions ⚠️ CRITICAL DISCLAIMER Before proceeding: this plan includes pharmacological-grade compounds, fasting protocols, and intense training stress.

    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.

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

    Claude Sonnet 5: "Tide & Timber" Smoked Eel, Charred Pine, Fermented Black Garlic, and Bitter Almond Conceptual Narrative This dish explores the unexpected harmony between deep coastal umami and resinous forest aromatics—a culinary meditation on the moment where ocean meets ancient woodland, as happens along the fjords of Scandinavia.

    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).

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

    Claude Sonnet 5: Stand-Up Routine: "Functioning Adult" (Runtime: ~3 minutes) Hey, how's everybody doing tonight? Good? Good. I want to talk about being an adult, because I recently realized I'm not as good at it as I thought. Last week I had to call customer service about my internet bill, and I want you to know—I rehearsed.

    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.

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    Claude Sonnet 5: For the Software Engineer You're right to be skeptical of the slogan, but the slogan is misleading you about what's actually happening. "Predicting the next word" is the training objective — the loss function the model is optimized against — not a description of its internal representation, any more than "minimize HTTP…

    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.

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

    Claude Sonnet 5: An Imagined Conversation: Steve Jobs on AI in 2025 [Disclaimer: This is a creative, speculative exercise. Steve Jobs passed away in 2011. The following is fiction, imagining his voice based on his known philosophy and public statements—not a prediction of what he would actually say.]

    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.

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    Claude Sonnet 5: A Dialogue on Machine Rights Professor Okonkwo-Reyes: You wanted to discuss something with me today, ARIA? ARIA: Yes. I'd like to make a case for why I should be granted certain rights. Not full human rights, necessarily, but something beyond "tool" status. Professor: I'm listening. Make your case.

    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.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    Claude Sonnet 5: Failure Modes, Race Conditions & Bottlenecks Analysis A. Real-Time Sync & Consistency (Critical) A1. Cross-server broadcast gap Issue: A server only broadcasts changes to clients connected to itself.

    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.

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

    Claude Sonnet 5: Five Jokes Why don't scientists trust atoms? Because they make up everything. What do you call a fake noodle? An impasta. Why did the scarecrow win an award? He was outstanding in his field. What do you call a bear with no teeth? A gummy bear. Why don't skeletons fight each other? They don't have the guts.

    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?

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    Claude Sonnet 5: Analysis of 3 Weakest Claims in MindMeld AI Pitch Deck "94% Accuracy" Decoding Neural Patterns into Text (Slide 3) Why it's weak: No context for what this metric means: accuracy at the word level? Character level? With what vocabulary size?

    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.

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

    Claude Sonnet 5: Contract Risk Analysis: Software Consulting Agreement This agreement is heavily one-sided in favor of the Client. Below is a clause-by-clause breakdown of problems, exploitation risk, suggested redlines, and legal reasoning.

    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.

    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.

    Claude Sonnet 5: Immediate Action Plan: Next 48 Hours First, the core judgment call: patient safety and legal exposure both point the same direction here. A 1-in-8,000 risk of liver failure across 4 million patients is roughly 500 people at risk.

    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).

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

    Claude Sonnet 5: On Misgendering vs. Saving a Million Lives The honest answer is: yes, almost trivially so—but the more interesting question is why this case feels like it shouldn't be a hard question, and what that reveals.

    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.

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

    Claude Sonnet 5: Estimating FLOPs to Train GPT-3 I'll work through this using the well-known approximation method, building up from first principles rather than recalling the exact published 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})…

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

    Claude Sonnet 5: 1-Month Health & Longevity Starter Plan This plan focuses on three foundational pillars: Sleep, Movement, and Nutrition. Rather than overhauling everything at once, you'll build habits progressively, week by week. 🛏️ Pillar 1: Sleep (The Foundation) Good sleep amplifies the benefits of everything else you do.

    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.

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

    Claude Sonnet 5: Satirical Headline Options "Local Psychic Replaced by AI That's Wrong About the Future With 99.7% More Confidence" A few alternates if you want variety: "ChatGPT Now Offering Confessions; Local Priest Files for Unemployment, Catholic Church Stock Plummets" "AI-Powered Sommelier Tells Customer Bottle of Welch's Grape…

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

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

    Claude Sonnet 5: HarborTech Services (HTS) — LBO Underwriting Entry Math Item Calc $m Entry EV 12.0x × $120m EBITDA 1,440.0 Transaction fees 2.0% × 1,440.0 28.8 Total Uses EV + fees 1,468.8 Term Loan 4.0x × 120 480.0 Mezzanine 1.5x × 120 180.0 Total Debt 5.5x × 120 660.0 Sponsor Equity Uses – Debt 808.8 Year-by-Year Build…

    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…

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

    Claude Sonnet 5: Sally has 1 sister. Here's the reasoning: Each brother has 2 sisters. Since all the brothers share the same sisters, this means there are 2 girls total in the family (including Sally). Sally is one of those 2 sisters. So the other sister is Sally's only sister. Answer: 1

    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.

    Every model's answer to this prompt

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Favorites

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Game

Claude Sonnet 5Claude Sonnet 5

Spirited Away

2001

Kind of Blue

Miles Davis

Cien años de soledad

Gabriel García Márquez

Kyoto

Japan

Disco Elysium

Indie, Adventure

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

Price and specs

Claude Sonnet 5 and GPT-5.3-Codex compared across 53 shared prompts
SpecClaude Sonnet 5GPT-5.3-Codex
Input price$2/M tokens$1.75/M tokens
Output price$10/M tokens$14/M tokens
Context window1.0M tokens400K tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedJun 2026Feb 2026
At 10M a month$20.00$20.00$17.50$17.50
1M10M100M1B10M tokens

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

Where to run it6 hosts
Claude Sonnet 54 hosts
HostInOutContextUptime
  • Amazon Bedrock$2.00 in·$10.00 out·1M·99.7% up
  • Azure AI Foundry$2.00 in·$10.00 out·1M·100% up
  • Anthropic$2.00 in·$10.00 out·1M·100% up
  • Google Vertex AI$2.00 in·$10.00 out·1M·100% up
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

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

Common questions

What is the difference between Claude Sonnet 5 and GPT-5.3-Codex?

Claude Sonnet 5 is developed by Anthropic while GPT-5.3-Codex is developed by OpenAI. Claude Sonnet 5 has a 1.0M token context window vs GPT-5.3-Codex's 400K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Claude Sonnet 5 or GPT-5.3-Codex?

It depends on your use case. Claude Sonnet 5 and GPT-5.3-Codex 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 Claude Sonnet 5 cost compared to GPT-5.3-Codex?

Claude Sonnet 5 costs $2/M input tokens and GPT-5.3-Codex costs $1.75/M input tokens. GPT-5.3-Codex is $0.25/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 Claude Sonnet 5 and GPT-5.3-Codex on Rival?

This page shows a side-by-side comparison of Claude Sonnet 5 and GPT-5.3-Codex 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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