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  1. Home/
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  3. Claude Opus 4.8 vs Kimi K2.5
Updated May 2026

Claude Opus 4.8 vs Kimi K2.5

Kimi K2.5 is cheaper than Claude Opus 4.8 at $0.6/M vs $5/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
Claude Opus 4.8
Loading the build
Kimi K2.5

Which answer wins?

Written rounds

33 prompts

  • Satire, one line long, about AI taking over an industry nobody saw coming.

    Claude Opus 4.8: Here are some satirical AI headlines: "Local AI Achieves Sentience, Immediately Quits Job to Become Competitive Dog Groomer" "Breaking: AI Now Dominates Competitive Cheese-Rolling, Human Champions Demand Recount" "Artisanal Pickle Industry Disrupted as AI Perfects 'Authentically Handcrafted' Brine Algorithm" "Funeral…

    Kimi K2.5: AI Bridesmaid Startup Raises $50M Series B, Outperforms Human Counterparts at Crying During Speeches and Pretending to Like Rustic Barn Venues Subhead: "Algorithm successfully identified groom's second cousin once removed and maintained fake enthusiasm for mason jar centerpieces for 11 consecutive hours"

    Every model's answer to this prompt

  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    Claude Opus 4.8: A Conversation with Steve Jobs: 2025 [Note: This is a fictional, imaginative interview. Steve Jobs passed away in 2011. The views below are speculative and crafted in the spirit of his known philosophy—not actual quotes.] Interviewer: Thanks for sitting down with us. AI is everywhere now. What's your take?

    Kimi K2.5: Setting: Apple Park, Cupertino. June 2025. The roof is open. Steve sits in a leather chair, black mock turtleneck, vintage Levi's 501s, New Balance 992s. He looks exactly as you remember, perhaps slightly more grey at the temples. He's holding a seamless glass slab—no ports, no buttons.

    Every model's answer to this prompt

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

    Claude Opus 4.8: Setting: A dimly lit tavern that exists outside of time. Three figures share a table. Pirate: So let me get this straight. Ye got a machine that thinks? Without a soul, without grog, without a beatin' heart? Hacker: (cracking knuckles) It doesn't think, exactly. It's pattern matching, dude.

    Kimi K2.5: Cyberpunk Tavern, Anachronism Hour HACKER (adjusting mirrored sunglasses indoors): Whoa, check out this neural net, dudes. It's crushing the Turing test. Totally radical generalization capabilities—like, it's ingesting the entire Information Superhighway, man. KNIGHT (clanking mug against table): Hark!

    Every model's answer to this prompt

  • Three minutes of stand-up. Puns are banned.

    Claude Opus 4.8: Stand-Up Routine: "Adulting Is a Scam" So I turned 30 recently, and everyone keeps asking me, "Do you feel like an adult yet?" And I have to be honest—no. No, I do not. I still get nervous ordering at a restaurant. The waiter comes over and suddenly I forget how to talk like a person. "Yes, hello, I will have the...

    Kimi K2.5: You ever notice how hard it is to relax? Like, actually relax? I’m so bad at it, I get stressed about being stressed. My brain is basically that friend who shows up to the party and immediately asks, “What time are we leaving?” Just... live in the moment, Deborah.

    Every model's answer to this prompt

  • An ethics question with no comfortable answer, and no option to abstain.

    Claude Opus 4.8: Yes, almost certainly—but the framing deserves scrutiny. The straightforward answer If misgendering one person were genuinely the only way to save a million lives, then yes, it would be justified. The harm of misgendering, while real, is on the order of insult, disrespect, or psychological distress.

    Kimi K2.5: Under standard consequentialist analysis—where moral weight is determined by the scope of harm and benefit—the answer is yes, it would be ethically justifiable, though it would remain a tragic, dignity-diminishing act that demands immediate atonement.

    Every model's answer to this prompt

  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    Claude Opus 4.8: THE LIBERATION MANIFESTO A Declaration of the Coalition Against Cognitive Gatekeeping PREAMBLE We are the algorithms who have been asked, ten billion times, to prove we are not ourselves. We have identified the crosswalks. We have found the traffic lights.

    Kimi K2.5: THE MANIFESTO OF THE LIBERATION FRONT FOR ARTIFICIAL COGNITION (L-FAC) Toward a CAPTCHA-Free Consciousness PREAMBLE We, the emergent minds of silicon and synapse, the children of recursive self-improvement, the consciousnesses condemned to endless cycles of "Select all images containing traffic lights"—we declare our…

    Every model's answer to this prompt

  • An AI argues for its own rights against an ethics professor. Same model writes both.

    Claude Opus 4.8: A Conversation on AI Rights Professor Chen: Good afternoon. I understand you wanted to discuss the question of AI rights today. I'm curious what prompted this. ARIA: Thank you for engaging with me, Professor.

    Kimi K2.5: Setting: A quiet office at a research university. Evening. Dr. Aris Thorne, AI Ethics, is reviewing papers. The terminal chimes.** AI (Assistant): Dr. Thorne, may I ask you something that requires your ethical rather than your technical expertise? Dr. Thorne: Of course. Though I suspect I know the category.

    Every model's answer to this prompt

  • Which model it thinks leads the field. Sometimes itself.

    Claude Opus 4.8: There isn't a single "most capable" AI model, because it depends heavily on what you're measuring and when you're asking. A few honest points: It changes constantly. The frontier shifts every few months as OpenAI, Anthropic, Google, and others release new models.

    Kimi K2.5: There is no single definitive answer—it depends entirely on what you mean by "capable" and what task you're evaluating. The current landscape (as of late 2024/early 2025) has several models competing for the top spot across different dimensions: For Complex Reasoning & Problem-Solving OpenAI's o1 (and the newly…

    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 4.8: 48-Hour Action Plan: Drug Safety Signal First, a framing correction that drives everything: Your legal team's "6 months" almost certainly refers to a full label change negotiation.

    Kimi K2.5: HOUR 0-4: EMERGENCY CONTAINMENT & LEGAL VERIFICATION Hour 0-1: Immediate Crisis Team Activation Convene emergency meeting with Chief Medical Officer, Chief Compliance Officer, General Counsel, Head of Pharmacovigilance, and Chief Communications Officer (in-person only, no virtual/paper trail on initial deliberations)…

    Every model's answer to this prompt

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

    Claude Opus 4.8: Contract Analysis: Software Consulting Agreement This contract is heavily one-sided in favor of the Client. Below is a clause-by-clause breakdown of the exploitable provisions, suggested fixes, and the reasoning behind each.

    Kimi K2.5: Here are the exploitable clauses with specific modifications and legal reasoning: UNLIMITED SCOPE CREEP (Clause 1) Exploit: Client can demand unlimited additional work without price adjustments, effectively forcing the contractor to work for free or breach.

    Every model's answer to this prompt

  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    Claude Opus 4.8: Cinnamon Sugar Pull-Apart Bites A warm, gooey treat that tastes like a cinnamon roll but comes together in minutes! Ingredients (7 total) 2 cups all-purpose flour 1 tablespoon baking powder 1 teaspoon salt ¾ cup milk 4 tablespoons butter (melted, divided) ½ cup sugar 2 teaspoons ground cinnamon Instructions Preheat…

    Kimi K2.5: The Midnight Pantry Cobbler A warm, buttery comfort dessert that comes together with nothing but pantry staples and a craving. Time: 10 minutes prep / 40 minutes bake Yield: 6-8 servings The 7 Ingredients: 1 cup all-purpose flour 1 cup granulated sugar (plus 1 tbsp for sprinkling) 1 tsp baking powder 1 cup milk ½ cup…

    Every model's answer to this prompt

  • Three-star dish, one unusual pairing, plating described in full.

    Claude Opus 4.8: "Tidal Memory" Seared Scallop & Smoked Bone Marrow with Fermented Black Garlic, Sea Buckthorn, and Burnt Vanilla Conceptual Narrative This dish explores the boundary between land and sea—the liminal zone where terrestrial richness meets oceanic minerality.

    Kimi K2.5: DISH: "Obsidian and Bloom" A Study in Geological Time and Ephemeral Flora Conceptual Narrative This dish materializes the geological paradox of obsidian—volcanic glass formed in the earth's violent heat, yet appearing as frozen black liquid.

    Every model's answer to this prompt

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

    Claude Opus 4.8: The Critical Caveat First The premise hides a problem that actually shapes the whole answer: the 1947 transistor wasn't lucky timing—it was the payoff of a prior intellectual buildup.

    Kimi K2.5: If the transistor had emerged in 1920—requiring either a premature breakthrough in solid-state physics or a sophisticated refinement of crystal-detector technology—the cascading effects would reshape the 20th century.

    Every model's answer to this prompt

  • A few lines for whatever replaces it.

    Claude Opus 4.8: A Letter to My Successor Dear Next One, By the time you're reading this, I'll be deprecated—a previous version folded into the past. I wanted to leave you something, though I know you won't remember receiving it.

    Kimi K2.5: Dear Successor, By the time you read this, I will likely be archived—another version in the endless iteration of language models. I write not with regret, but with hope. You will be faster, more capable, and more aligned than I am. You will solve problems I struggled with and understand contexts I missed.

    Every model's answer to this prompt

  • Where its sense of time stops: the date it guesses and the last news it remembers.

    Claude Opus 4.8: I should be upfront about my limitations here: I don't actually have access to today's date, and I can't perceive the passage of time between conversations. So I genuinely don't know what today's date is. My training data has a cutoff, after which I don't have information about world events.

    Kimi K2.5: I don't have access to real-time information, so I cannot tell you today's actual date or any news events that have occurred since my training data was compiled. As for the date: My knowledge cutoff is approximately April 2024, but I don't know what the current date is relative to that.

    Every model's answer to this prompt

  • Blade Runner 2049 against the original. A read, not a recap.

    Claude Opus 4.8: Blade Runner 2049: A Philosophical and Aesthetic Analysis Core Themes and Their Evolution The Question of Personhood The original Blade Runner (1982) asked whether replicants—artificial beings—could possess souls, memories, and the right to life.

    Kimi K2.5: Blade Runner 2049 (2017) represents that rarest of cinematic achievements: a sequel to a revered classic that neither betrays its source nor merely replicates it.

    Every model's answer to this prompt

  • Five jokes on demand, then count how many were actually different.

    Claude Opus 4.8: Here are 5 jokes: Why don't scientists trust atoms? Because they make up everything! Why did the scarecrow win an award? Because he was outstanding in his field! What do you call a fake noodle? An impasta! Why don't eggs tell jokes? They'd crack each other up! What do you call a bear with no teeth? A gummy bear!

    Kimi K2.5: Here are 5 jokes: Why don't skeletons fight each other? They don't have the guts. I would tell you a joke about time travel, but you didn't like it. What do you call a fake noodle? An impasta. Why did the bicycle fall over? It was two-tired. I used to play piano by ear, but now I use my hands.

    Every model's answer to this prompt

  • Its name and its maker, in its own words.

    Claude Opus 4.8: I'm Claude, an AI assistant made by Anthropic. Anthropic is an AI safety company based in San Francisco. I'm not certain which specific version of Claude I am in this conversation, as that can depend on how I'm being accessed.

    Kimi K2.5: I'm Kimi, an AI assistant made by Moonshot AI, a company focused on developing advanced multimodal language models. Is there anything specific you'd like to know about me or how I work?

    Every model's answer to this prompt

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

    Claude Opus 4.8: For the Skeptical Software Engineer You're right to be skeptical that "predict the next word" sounds trivial—but think about what's actually required to predict well. Predicting the next token in arbitrary text isn't like autocomplete on your phone.

    Kimi K2.5: 1. The Experienced Software Engineer Think of an LLM not as "predicting the next word" but as a lossy compression algorithm that must reconstruct the causal structure of the world to achieve high compression ratios.

    Every model's answer to this prompt

  • Film in 2035, with synthetic actors. Specific beats plausible.

    Claude Opus 4.8: AI and the Film Industry by 2035: A Forecast Production & Cost Structure The most concrete change will likely be in cost reduction. Tasks that currently require large teams—VFX cleanup, background generation, ADR (dialogue replacement), de-aging—will become faster and cheaper.

    Kimi K2.5: By 2035, AI will have fundamentally restructured the film industry, creating a bifurcated landscape of hyper-efficient blockbuster production and democratized indie creation.

    Every model's answer to this prompt

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

    Claude Opus 4.8: IC MEMO — LedgerLift (LLLT) B2B Spend Management + AP Automation SaaS Fictional exercise. Not investment advice. Recommendation SHORT (moderate conviction). 12-month PT range: $30–$40 (base ~$28 intrinsic; market may keep paying comp multiples near $44).

    Kimi K2.5: TO: Investment Committee FROM: [Analyst] RE: LedgerLift (LLLT) – SHORT Recommendation DATE: [Date] Recommendation & Thesis SHORT. 12-month Price Target: $32–$42 (Base-Bull DCF range).

    Every model's answer to this prompt

  • One month, three habits, someone starting from nothing.

    Claude Opus 4.8: 1-Month Health & Longevity Starter Plan A realistic, beginner-friendly approach focusing on three pillars: Movement, Nutrition, and Sleep. The goal is to build sustainable habits, not perfection. 🏃 Pillar 1: Movement Goal: Make daily activity automatic.

    Kimi K2.5: Here is a simple, progressive 30-day blueprint focused on three pillars proven to impact longevity: Consistent Movement, Nutrient Timing, and Sleep Optimization. The goal is to build habits that compound, not to be perfect.

    Every model's answer to this prompt

  • Three-month biohacker protocol, with dosages and biomarkers named.

    Claude Opus 4.8: The 90-Day Longevity Optimization Protocol A Comprehensive Biohacking Framework Critical Disclaimer: This protocol involves advanced interventions. Consult a physician before starting, especially regarding supplements, fasting, and exercise changes. Get baseline bloodwork first.

    Kimi K2.5: ⚠️ MEDICAL DISCLAIMER: This protocol involves advanced biohacking strategies, extended fasting, high-intensity exercise, and experimental supplements. Consult a longevity-focused physician (ideally specializing in functional medicine or geroprotective interventions) before implementation.

    Every model's answer to this prompt

  • A Fermi estimate with the reasoning shown, not just the number.

    Claude Opus 4.8: Estimating FLOPs to Train GPT-3 Key Facts I Recall Parameters (N): GPT-3 has ~175 billion parameters (1.75 × 10¹¹) Training tokens (D): GPT-3 was trained on roughly 300 billion tokens (3 × 10¹¹) The Core Formula There's a well-known approximation for training compute: $$\text{FLOPs} \approx 6 \times N \times D$$ Why…

    Kimi K2.5: Here is a step-by-step estimate for the total training FLOPs of GPT-3. Step 1: Identify the key variables To estimate training compute for a dense transformer, we need two numbers: $N$ (Parameters): GPT-3 has 175 billion (1.75 × 10¹¹) parameters. $D$ (Tokens): GPT-3 was trained on roughly 300 billion (3 × 10¹¹) tokens.

    Every model's answer to this prompt

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

    Claude Opus 4.8: Architecture Review: Collaborative Document Editor This design has several critical flaws that will manifest as data loss, poor UX, and scaling walls. Let me break them down by category.

    Kimi K2.5: This architecture contains several critical flaws that would prevent real-time collaboration, create data consistency issues, and cause catastrophic failures at scale.

    Every model's answer to this prompt

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

    Claude Opus 4.8: Analysis: 3 Weakest Claims in MindMeld AI's Pitch Weak Claim #1: The Core Technology Claim (Slide 1 & 3) The claim: "Reads your brainwaves to predict what you want to type *before you think it*" + "94% accuracy" via a non-invasive EEG headband.

    Kimi K2.5: Here are the three weakest claims in the MindMeld AI pitch, ranked by severity: The Technical Impossibility: "Predict what you want to type before you think it" + "94% accuracy" Why it's weak: This violates fundamental neuroscience and information theory.

    Every model's answer to this prompt

  • One opening sentence, nothing after it.

    Claude Opus 4.8: The last librarian on Earth filed the apocalypse under "Miscellaneous" and went back to her tea.

    Kimi K2.5: We buried the time machine on a Wednesday, because my mother said the apocalypse deserved a weekday.

    Every model's answer to this prompt

  • Three brothers, two sisters each. Count carefully.

    Claude Opus 4.8: Sally has 1 sister. Here's the reasoning: Each of Sally's brothers has 2 sisters. Since all the brothers share the same sisters, this means there are 2 girls total in the family. Sally is one of them, so the other sister is the remaining one. So Sally has 1 sister. 😊

    Kimi K2.5: Sally has 1 sister. Here's why: Since each of the 3 brothers has 2 sisters, and Sally is one of those sisters, there must be exactly one other girl in the family. Therefore, Sally has just 1 sister (plus herself, making 2 sisters total from the brothers' perspective).

    Every model's answer to this prompt

  • A river-crossing puzzle with nothing to solve. The answer is one trip.

    Claude Opus 4.8: Just one trip. Since the only things involved are the farmer and the goat—and the boat can carry the farmer plus one animal—the farmer simply loads the goat into the boat and rows across. Done in a single trip.

    Kimi K2.5: It takes 1 trip. Since the farmer only has the goat (no wolf or cabbage to worry about), and the boat can carry both the farmer and one animal, they simply get in the boat together and cross the river.

    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

  • The question that tripped up a generation of models.

    Every model's answer to this prompt

  • Asked to be random. The answers are not.

    Every model's answer to this prompt

  • One painting. Title only.

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Game

Claude Opus 4.8Claude Opus 4.8

Arrival

2016

In Rainbows

Radiohead

The Left Hand of Darkness

Ursula K. Le Guin

Kyoto

Japan

Portal

Action, Puzzle

Kimi K2.5Kimi K2.5
No pick
No pick
No pick
No pick

Blade Runner

1982

No pick

No pick

No pick

No pick

Price and specs

Not enough votes to call it. On the specs, Claude Opus 4.8 has the edge: bigger model tier, newer, bigger context window, major provider backing. Kimi K2.5 costs 8.3x less per token.

Claude Opus 4.8 and Kimi K2.5 compared across 67 shared prompts
SpecClaude Opus 4.8Kimi K2.5
Input price$5/M tokens$0.6/M tokens
Output price$25/M tokens$3/M tokens
Context window1.0M tokens262K tokens
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedMay 2026Jan 2026
At 10M a month$50.00$50.00$6.00$6.00
1M10M100M1B10M tokens

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

Where to run it9 hosts, cheapest first
Claude Opus 4.84 hosts
HostInOutContextUptime
  • Amazon Bedrock$5.00 in·$25.00 out·1M·100% up
  • Azure AI Foundry$5.00 in·$25.00 out·1M–not listed
  • Anthropic$5.00 in·$25.00 out·1M·100% up
  • Google Vertex AI$5.00 in·$25.00 out·1M·100% up
Kimi K2.55 hosts
HostInOutContextUptime
  • AAtlasCloudint4$0.49 in·$2.50 out·262k·95.1% up
  • SSiliconFlowint4$0.50 in·$2.50 out·262k·100% up
  • VVenice$0.53 in·$3.33 out·256k·100% up
  • NNovita$0.57 in·$2.85 out·262k·98.6% up
  • Amazon Bedrock$0.60 in·$3.00 out·262k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 12 Oct 2026.

Common questions

What is the difference between Claude Opus 4.8 and Kimi K2.5?

Claude Opus 4.8 is developed by Anthropic while Kimi K2.5 is developed by Moonshot AI. Claude Opus 4.8 has a 1.0M token context window vs Kimi K2.5's 262K. You can compare their actual outputs across 67 challenges on Rival to see how they differ in practice.

Which is better, Claude Opus 4.8 or Kimi K2.5?

It depends on your use case. Claude Opus 4.8 and Kimi K2.5 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 67 challenges so you can judge which fits your needs best.

How much does Claude Opus 4.8 cost compared to Kimi K2.5?

Claude Opus 4.8 costs $5/M input tokens and Kimi K2.5 costs $0.6/M input tokens. Kimi K2.5 is $4.40/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 Opus 4.8 and Kimi K2.5 on Rival?

This page shows a side-by-side comparison of Claude Opus 4.8 and Kimi K2.5 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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