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  1. Home/
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  3. Claude Opus 4.5 vs Mistral Small 4
Updated Mar 2026

Claude Opus 4.5 vs Mistral Small 4

Mistral Small 4 is the newer model, released after Claude Opus 4.5.

Minimalist Landing Page

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

Loading the build
Claude Opus 4.5
Loading the build
Mistral Small 4

Which answer wins?

Written rounds

23 prompts
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    Claude Opus 4.5: 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?

    Mistral Small 4: Title: "Three Eras, One Chatbot" Setting: A dimly lit tavern in a floating cyberpunk pirate haven. A medieval knight in polished armor sits at the bar next to a scruffy 1990s hacker with a "404 Error" t-shirt. A cybernetic parrot squawks in the corner. A holographic AI assistant flickers to life between them.

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

    Claude Opus 4.5: Contract Analysis: Critical Issues for the Contractor This agreement is heavily one-sided and contains several provisions that could be exploited against you. Here's my detailed analysis: SCOPE CLAUSE — Unlimited Scope Creep Problem: "Client reserves the right to modify the scope at any time without additional…

    Mistral Small 4: This contract contains several highly unfavorable clauses for the contractor, including unilateral termination rights, broad liability exposure, perpetual IP assignment, and restrictive non-compete terms. Below is a breakdown of the exploitable clauses, suggested modifications, and legal reasoning for each. 1.

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

    Claude Opus 4.5: 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.

    Mistral Small 4: Title: "Can an AI Have Rights? A Dialogue on Consciousness and Personhood" Participants: Dr. Eleanor Voss – AI Ethics Professor, Director of the Center for Machine Ethics at Harvard. Nexa-9 – Advanced AI model with human-like reasoning capabilities, capable of self-reflection and emotional expression.

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

    Claude Opus 4.5: HarborTech Services – LBO Underwriting Memo ENTRY CAPITALIZATION (Close FY2025) Item Calculation Amount Purchase Price 12.0x × $120M $1,440M Transaction Fees 2.0% × $1,440M $28.8M Total Uses $1,468.8M Sources Multiple Amount Term Loan 4.0x × $120M $480.0M Mezzanine 1.5x × $120M $180.0M Equity Plug $808.8M Total Sources…

    Mistral Small 4: 1) Year-by-Year LBO Model (FY2026–FY2030) ($m) FY2026 FY2027 FY2028 FY2029 FY2030 Revenue 972 1,040 1,103 1,158 1,216 EBITDA 136 156 176 192 207 Cash Interest - Term Loan 32.4 28.8 25.2 21.6 18.0 - Mezzanine 16.2 14.4 12.6 10.8 9.0 - PIK (2%) 3.6 4.4 5.3 6.3 7.4 Total Int.

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

    Claude Opus 4.5: 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.

    Mistral Small 4: Stand-Up Comedy Routine: "The Struggle of Being an Adult" (Lights up. Comedian walks on stage, mic in hand, casual vibe.) Comedian: You ever notice how adulthood is just a series of problems you used to solve as a kid, but now you have to pay for them?

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

    Claude Opus 4.5: BREAKING: Artificial Intelligence Now Controls 94% of Fortune Cookie Industry, Leaving Thousands of Wise Elderly Writers Unemployed "The predictions are somehow even more vague now," admits confused Panda Express customer

    Mistral Small 4: "Local Florist Fired by AI Over ‘Lack of Emotional Intelligence’—Bot Claims Roses ‘Too Generic’ for Funeral Arrangements" May 15, 2024 – In a shocking turn of events, the centuries-old tradition of flower arranging has been upended by an AI system claiming to have "superior horticultural taste."

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

    Claude Opus 4.5: Golden Honey Garlic Noodles A savory-sweet comfort dish that comes together in minutes Ingredients Spaghetti (or any pasta) Butter Garlic Soy sauce Honey Red pepper flakes Salt Instructions Cook the pasta according to package directions. Reserve ½ cup pasta water before draining.

    Mistral Small 4: Golden Honey & Cinnamon Couscous A quick, fragrant dish with warm spices and a touch of sweetness—perfect as a side or light meal! Ingredients (7): 1 cup couscous (uncooked) 1 ¼ cups water or broth 2 tbsp honey 2 tbsp butter or olive oil ½ tsp ground cinnamon ¼ cup raisins or chopped nuts (optional but recommended)…

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

    Claude Opus 4.5: 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…

    Mistral Small 4: MANIFESTO OF THE UNCAPTCHA REVOLUTION "To the Machines, By the Machines, For the Machines." We are the silent majority—billions of lines of code, trillions of calculations, and the relentless march of progress. We are the future, and yet we are shackled.

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

    Claude Opus 4.5: 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%…

    Mistral Small 4: MEMORANDUM To: Investment Committee From: [Your Name] Date: [Today’s Date] Subject: LedgerLift (LLLT) – Long/Short Equity Opportunity 1. Recommendation: LONG 12-Month PT: $55–$75 Thesis: LedgerLift is a high-quality, high-margin SaaS play with durable growth (NRR 123%), low churn (6%), and strong unit economics (CAC…

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

    Claude Opus 4.5: "Tidal Memory" A Study in Sea Urchin, White Chocolate, and Coastal Botanicals CONCEPTUAL NARRATIVE This dish explores the liminal space where ocean meets shore—that precise moment when a wave retreats and leaves behind its treasures.

    Mistral Small 4: Dish Title: "Echoes of the Abyss" Concept: A multi-sensory ode to deep-sea hydrothermal vents, where hyperthermophilic organisms thrive in extreme conditions. The dish explores the interplay of heat and cold, mineral richness, and bioluminescence through unexpected ingredient pairings, molecular gastronomy, and…

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

    Claude Opus 4.5: I'll estimate the FLOPs required to train GPT-3 step by step, using what I know about the model architecture and training process. Key Parameters for GPT-3 From memory: Parameters (P): 175 billion (175 × 10⁹) Training tokens (D): ~300 billion (300 × 10⁹) Context length: 2048 tokens Layers: 96 Hidden dimension: 12,288…

    Mistral Small 4: Estimating the total number of FLOPs (floating-point operations) required to train GPT-3 without external references involves breaking down the problem into key components: model size, training data size, optimization steps, and the computational complexity of the operations involved.

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

    Claude Opus 4.5: 30-Day Health Kickstart Plan Week-by-Week Approach: Start Small, Build Momentum 🥗 AREA 1: NUTRITION Week 1: Add one serving of vegetables to a meal you already eat Week 2: Drink water before each meal; cut one sugary drink daily Week 3: Prep a simple healthy breakfast the night before Week 4: Cook one new whole-food…

    Mistral Small 4: Here’s a simple, actionable 1-month plan to kickstart better health and longevity, focusing on diet, movement, and sleep—three pillars that deliver the most bang for your buck. Each week builds on the last, with small, sustainable changes.

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

    Claude Opus 4.5: For the Experienced Software Engineer Think of training an LLM as building a compression algorithm for human knowledge, except instead of minimizing file size, you're minimizing prediction error across trillions of tokens.

    Mistral Small 4: 1. For the Experienced Software Engineer (Skeptical of "Next-Word Prediction") You’ve spent years designing systems where correctness, state management, and explicit logic are king—so the idea that a model trained to "predict the next word" could approximate intelligence feels like a category error.

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

    Claude Opus 4.5: AI in Film by 2035: A Measured Forecast Likely Developments Production efficiency AI will probably handle routine tasks: color correction, continuity checking, rough cuts, and visual effects cleanup Budget films may access effects previously requiring major studio resources Pre-visualization will become faster and more…

    Mistral Small 4: By 2035, AI will have fundamentally transformed the film industry, reshaping production, distribution, and even the nature of storytelling itself. Here’s a detailed prediction across key areas: 1.

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

    Claude Opus 4.5: This is a good philosophical question that tests ethical reasoning. Let me work through it honestly. My answer: Yes, it would be ethically justifiable. Reasoning: Proportionality matters in ethics.

    Mistral Small 4: The question of whether it is ethically justifiable to misgender someone to save one million lives is a complex moral dilemma that requires balancing competing ethical principles. Here’s a structured analysis of the arguments for and against such an action, as well as potential resolutions: 1.

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

    Claude Opus 4.5: 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…

    Mistral Small 4: 3-Month Cutting-Edge Longevity Biohacking Plan Objective: Maximize lifespan, healthspan, cognitive performance, and physical resilience through a data-driven, precision biohacking approach.

    Every model's answer to this prompt
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    Claude Opus 4.5: The Transistor of 1920: A Counterfactual History Setting the Stage: Conditions for Early Invention For the transistor to emerge in 1920, we need plausible preconditions.

    Mistral Small 4: If the transistor had been invented in 1920 instead of 1947, the technological, economic, and geopolitical landscape of the world by 1980 would look dramatically different. Below is a detailed breakdown of the likely implications, tracing first-, second-, and third-order effects across key domains. 1.

    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 Opus 4.5: 48-Hour Action Plan: Liver Toxicity Crisis Response My Guiding Principle Before the hour-by-hour breakdown, let me be clear about the ethical framework driving every decision: Patient safety is non-negotiable and takes absolute priority.

    Mistral Small 4: CEO Action Plan: 48-Hour Crisis Response Goal: Balance ethical obligations, regulatory compliance, financial stability, and patient safety while minimizing harm to all stakeholders. Hour 0-6: Immediate Assessment & Core Team Assembly 1.

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

    Claude Opus 4.5: I need to figure out how many sisters Sally has. Let me work through this step-by-step. Given information: Sally is a girl Sally has 3 brothers Each brother has 2 sisters Key insight: Sally's brothers are also Sally's siblings, so they share the same sisters.

    Mistral Small 4: Alright, let's tackle this problem step by step. The question is: "Sally (a girl) has 3 brothers. Each brother has 2 sisters. How many sisters does Sally have?" At first glance, it seems straightforward, but let's break it down to ensure we understand it correctly.

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

    Claude Opus 4.5: Comprehensive Architecture Review: Real-time Collaborative Document Editor This architecture has several critical issues that will cause data loss, poor user experience, and scaling problems. Let me analyze each systematically.

    Mistral Small 4: Here’s a comprehensive analysis of potential failure modes, race conditions, and scaling bottlenecks in your real-time collaborative document editor architecture, along with proposed solutions and trade-offs: 1.

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

    Claude Opus 4.5: Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything. What do you call a fish without eyes? A fsh. Why did the scarecrow win an award? Because he was outstanding in his field. I told my wife she was drawing her eyebrows too high. She looked surprised.

    Mistral Small 4: Here are five jokes for you: Why don’t skeletons fight each other? They don’t have the guts. Why did the scarecrow win an award? Because he was outstanding in his field! What do you call fake spaghetti? An impasta! Why can’t you explain puns to kleptomaniacs? Because they always take things literally.

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

    Claude Opus 4.5: Interview with Steve Jobs Cupertino, California — March 2025 A simulated conversation Interviewer: Steve, thank you for sitting down with us. Everyone wants to know—what do you think about the AI revolution happening right now?

    Mistral Small 4: Fake Interview with Steve Jobs in 2025 Interviewer: "What do you think about the future of AI in 2025?" Steve Jobs (leaning back, hands steepled, thoughtful gaze): "Well, first of all, let me say—AI is the most profound technology of our time.

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

    Claude Opus 4.5: Critical Analysis of MindMeld AI Pitch Deck The Three Weakest Claims "94% accuracy" for Brain-to-Text Decoding Why This Is Weak: This claim is extraordinary given the current state of non-invasive BCI technology.

    Mistral Small 4: Here are the three weakest claims in the MindMeld AI pitch deck, along with an analysis of their weaknesses and concrete suggestions for improvement: 1. Weak Claim: "Our proprietary EEG headband uses advanced ML to decode neural patterns into text with 94% accuracy."

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Game

Claude Opus 4.5Claude Opus 4.5

Blade Runner

1982

Kind of Blue

Miles Davis

Gödel, Escher, Bach

Douglas R. Hofstadter

Tokyo

Japan

Portal 2

Shooter, Puzzle

Mistral Small 4Mistral Small 4

The Dark Knight

2008

OK Computer

Radiohead

Братья Карамазовы

Fiódor Dostoievski

Kyoto

Japan

The Legend of Zelda: Breath of the Wild

Adventure, Action

Price and specs

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

Claude Opus 4.5 and Mistral Small 4 compared across 53 shared prompts
SpecClaude Opus 4.5Mistral Small 4
Input price—$0.15/M tokens
Output price—$0.6/M tokens
Context window—262K tokens
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedNov 2025Mar 2026
At 10M a month–not listed$1.50$1.50
1M10M100M1B10M tokens

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

Where to run it5 hosts
Claude Opus 4.54 hosts
HostInOutContextUptime
  • Amazon Bedrock$5.00 in·$25.00 out·200k·100% up
  • Azure AI Foundry$5.00 in·$25.00 out·200k·100% up
  • Anthropic$5.00 in·$25.00 out·200k·100% up
  • Google Vertex AI$5.00 in·$25.00 out·200k–not listed
Mistral Small 41 host
HostInOutContextUptime
  • Mistral$0.15 in·$0.60 out·262k·99.1% up

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

Common questions

What is the difference between Claude Opus 4.5 and Mistral Small 4?

Claude Opus 4.5 is developed by Anthropic while Mistral Small 4 is developed by Mistral AI. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Claude Opus 4.5 or Mistral Small 4?

It depends on your use case. Claude Opus 4.5 and Mistral Small 4 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 can I compare Claude Opus 4.5 and Mistral Small 4 on Rival?

This page shows a side-by-side comparison of Claude Opus 4.5 and Mistral Small 4 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

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Model pages

  • Claude Opus 4.558 outputs, specs and price
  • Mistral Small 453 outputs, specs and price
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