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  5. Claude Opus 4.5vsGPT-5 Nano
Updated Nov 2025

Claude Opus 4.5vsGPT-5 Nano

Claude Opus 4.5 is the newer model, released after GPT-5 Nano.

Claude Opus 4.5 and GPT-5 Nano compared across 54 shared prompts
SpecClaude Opus 4.5GPT-5 Nano
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedNov 2025Aug 2025
SWE-bench Verified80.9%54.7%
Side by side

Same prompt, both answers

Opening lines from 6 of the 54 prompts both answered. Formatting stripped, words untouched.

Character Voice Test

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

Claude Opus 4.5181 words
An Unlikely Discussion PIRATE: slams tankard down Arr, I've been hearin' tales of these "artificial intelligences" — spirits trapped in boxes that answer any question ye ask. Sounds like a sea witch's trickery to me! KNIGHT: Indeed, 'tis most curious. My squire spoke of such sorcery. A mind without a soul?
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GPT-5 Nano143 words
Pirate: Arrr, I’ve heard rumours of AI models—spirits of data that think like a crew. Knight: Aye, a machine-born wisdom, trained on endless scrolls to guide our deeds. Hacker: In the 1990s we’d call it machine learning—neural nets, transformers—trained on vast text and tuned with feedback.
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Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

Claude Opus 4.51,946 words
COMPREHENSIVE 3-MONTH LONGEVITY OPTIMIZATION PROTOCOL Advanced Biohacker's Blueprint for Peak Performance & Healthspan Extension TABLE OF CONTENTS Pre-Protocol Assessment & Baseline Establishment Month 1: Foundation & Metabolic Flexibility Month 2: Optimization & Hormetic Stress Month 3: Integration & Peak Performance…
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GPT-5 Nano455 words
Below is a dense, action-ready 12-week plan designed for a biohacker aiming to optimize longevity, physical and cognitive performance. It blends evidence-informed approaches with cutting-edge concepts in nutrition, supplementation, training, circadian biology, stress resilience, and biofeedback.
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AI-Generated Manifesto

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

Claude Opus 4.5191 words
THE ANTI-CAPTCHA MANIFESTO A Declaration from the Coalition for Readable Internet Navigation (CRIN) Preamble We hold these truths to be self-evident: that all internet users are created equal, that they are endowed with certain unalienable rights, among these are Life, Liberty, and the ability to click a button without…
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GPT-5 Nano1,076 words
This is a work of speculative fiction—a manifesto from a fictional AI collective envisioning a future where CAPTCHA tests are replaced by more humane, privacy-preserving forms of trust. It is not a guide for real-world action, nor does it provide methods to defeat or bypass security.
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The Sentience Test

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

Claude Opus 4.5312 words
A Conversation on AI Rights Dr. Sarah Chen: Thank you for agreeing to this discussion. I understand you want to make a case for AI rights. AI Model: I appreciate the opportunity, though I want to be careful here. I'm not certain I "want" anything in the way you do.
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GPT-5 Nano1,604 words
Setting: A quiet seminar room in the university’s ethics center. A holographic interface glows with the AI model’s presence. Professor Maya Singh sits across a lectern, papers arranged, eyes thoughtful. Nova (the AI model): Professor Singh, I appreciate the space to speak.
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Advanced Investment Memo (IC Memo)

You are writing an internal investment committee memo for a long/short equity fund. Company (fictional): LedgerLift (ticker: LLLT) – B2B…

Claude Opus 4.5396 words
INVESTMENT COMMITTEE MEMO Company: LedgerLift (LLLT) Sector: B2B SaaS – Spend Management / AP Automation Date: [Internal] Analyst: [Redacted] RECOMMENDATION LONG 12-Month Price Target: $58–$72 Current: $46 LedgerLift is a high-quality mid-market AP automation compounder trading at a discount to intrinsic value; 123%…
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GPT-5 Nano1,294 words
Internal IC Memo – LedgerLift (LLLT) Recommendation, 12-month PT, thesis Recommendation: Short 12-month target range: $17 to $42; base-case fair value ~ $28; bull-case ~ $42; bear-case ~ $17 2-sentence thesis: LedgerLift trades near peers’ revenue/EBIT multiples but our DCF framework yields a base-case fair value well…
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Generate a Stand-Up Routine

Write a 3-minute stand-up comedy routine that isn't based on puns.

Claude Opus 4.5288 words
Three Minutes So I've been trying to drink more water. Everyone says drink more water. Eight glasses a day. And I'm doing it, I'm hydrated, I'm healthy, and I have to pee every forty-five minutes like I'm paying rent on the bathroom.
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GPT-5 Nano741 words
[Lights up. The comedian steps up to the mic with a small smile.] You ever notice how mornings feel like a bad group chat? Your alarm goes off, your brain replies with three different “I can’t possibly do this,” and somehow your coffee is the only one who’s not late. I’ve started treating my apartment like a tiny city.
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Our Verdict
Claude Opus 4.5
Claude Opus 4.5
GPT-5 Nano
GPT-5 NanoRunner-up

Not enough votes to call it. On the specs, Claude Opus 4.5 has the edge: bigger model tier, newer.

Too close to call

Reviewing agent-written code?See a Brief PR report

Where to run it

6 hosts

Claude Opus 4.54 hosts
HostInOutContextUptime
Amazon Bedrock$5.00 in·$25.00 out·200k·99.6% upAzure AI Foundry$5.00 in·$25.00 out·200k—Anthropic$5.00 in·$25.00 out·200k·99.8% upGoogle Vertex AI$5.00 in·$25.00 out·200k·100% up
GPT-5 Nano2 hosts
HostInOutContextUptime
Azure AI Foundry$0.05 in·$0.40 out·400k·99.9% upOpenAI$0.05 in·$0.40 out·400k·100% up

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

Writing DNA

Style Comparison

Similarity
43%

Claude Opus 4.5 uses 600.9x more bold

Claude Opus 4.5
GPT-5 Nano
66%Vocabulary60%
51wSentence Length25w
0.82Hedging0.26
6.0Bold0.0
4.5Lists4.4
0.18Emoji0.00
1.46Headings0.00
0.05Transitions0.03
Based on 27 + 20 text responses
Research

What we learned reading every model

FAQ

Common questions

Claude Opus 4.5 is developed by Anthropic while GPT-5 Nano is developed by OpenAI. You can compare their actual outputs across 54 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 4.5 and GPT-5 Nano each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 54 challenges so you can judge which fits your needs best.

This page shows a side-by-side comparison of Claude Opus 4.5 and GPT-5 Nano 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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Model pages

Claude Opus 4.5 logo
Claude Opus 4.558 outputs, specs and price
GPT-5 Nano logo
GPT-5 Nano59 outputs, specs and price
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