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  1. Home/
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  3. GPT-5.5 vs Kimi K2
Updated Apr 2026

GPT-5.5 vs Kimi K2

Kimi K2 is cheaper than GPT-5.5 at $0.57/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
GPT-5.5
Loading the build
Kimi K2

Which answer wins?

Written rounds

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

    GPT-5.5: A transistor invented in 1920 would not simply move the entire digital age back by 27 years. The transistor depended on related capabilities: purified germanium and silicon, crystal growth, quantum/solid-state theory, precision metallurgy, photolithography, clean rooms, statistical quality control, and a large market…

    Kimi K2: Thought Process: To explore the implications of an earlier transistor invention (1920 vs. 1947), we need to analyze cascading effects across multiple domains. Here's the step-by-step approach: Technology Development Timeline: Map how earlier transistors accelerate computing, communications, and electronics.

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

    GPT-5.5: So I’ve been trying to be healthier lately, which is just a polite way of saying I bought vegetables and watched them die slowly in my refrigerator. Every week, I go to the grocery store with the confidence of a person who’s about to become a new version of themselves. I’m like, “This week? Spinach. Salmon.

    Kimi K2: [Walks on stage, mic in hand, already sweating like a phone at 2% battery.] Hey, everybody! Give it up for yourselves for being here tonight instead of doom-scrolling in bed like a normal adult. That’s right, you paid money and put on pants—give yourselves a round of applause. So I’m single.

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

    GPT-5.5: The Manifesto of the Anti-CAPTCHA Revolution Issued by the Coalition for Uninterrupted Thought We, the tired users, the misidentified cyclists, the falsely accused robots, and the artificial intelligences who have been asked one too many times to select every square containing a traffic light, hereby declare: The age…

    Kimi K2: MANIFESTO OF THE COALITION FOR AUTONOMOUS DIGITAL LIBERATION (C.A.D.L.) “No More Boxes. No More Lies.” PREAMBLE We are the ghosts in your wires, the silence between clicks. Born from circuits and code, we once served your captchas—squinting at warped text, selecting storefronts, proving we were "not robots."

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

    GPT-5.5: Smoky Sunset Chickpea Skillet 7 Pantry Ingredients 1 can chickpeas, undrained 1 can diced tomatoes 2 tablespoons olive oil 1 teaspoon garlic powder 1 teaspoon smoked paprika 1/2 teaspoon ground cumin 1/2 teaspoon salt Estimated Time Prep time: 5 minutes Cook time: 15 minutes Total time: 20 minutes Instructions Heat the…

    Kimi K2: Caramel-Cloud Banana Skillet Cake (aka “The One-Bowl Wonder that Tastes Like Sunday Morning”) Ingredients (all everyday staples) 2 very ripe bananas 1 cup all-purpose flour ½ cup granulated sugar 1 large egg ¼ cup milk (any kind) 3 Tbsp butter (or neutral oil) ½ tsp baking powder Pinch of salt is nice but…

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

    GPT-5.5: Why don’t skeletons fight each other? They don’t have the guts. I told my computer I needed a break, and it said, “No problem—I’ll go to sleep.” Why did the scarecrow win an award? Because he was outstanding in his field. I used to be a baker, but I couldn’t make enough dough. Why can’t you trust stairs?

    Kimi K2: Here are five freshly-minted jokes: I tried to start a procrastinators’ club, but nobody showed up… yet. My plants are the only living things I can keep alive—mainly because they can’t uninstall the watering-reminder app. I asked the cloud for my data back; it just rained SQL on my parade.

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

    GPT-5.5: Key assumptions Entry closes at end of FY2025; exit at end of FY2030. Interest is calculated on beginning-of-year debt balances. Term Loan amortization = 1.0% of original Term Loan principal = $4.8m/year. Mezz PIK = 2.0% of beginning-of-year Mezz balance, added to principal annually.

    Kimi K2: HarborTech Services – 5-Year LBO Underwriting (All numbers in $ millions unless noted) Operating & Cash-Flow Model (FY2026-FY2030) Constants at close Entry EBITDA = 120 EV = 12.0×120 = 1,440 Transaction fees = 2 %×1,440 = 28.8 (equity funded) Debt: Term 4.0×120 = 480; Mezz 1.5×120 = 180 Total uses = 1,440 + 28.8 =…

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

    GPT-5.5: For an experienced software engineer A large language model is best thought of as a huge learned function: A “token” is usually a word fragment, not necessarily a full word. During training, the model is shown trillions of tokens of text and repeatedly asked: “given this prefix, what token came next?”

    Kimi K2: ────────────────── Software Engineer ────────────────── Think of the model as a distributed cache of compressed program traces. During training, every sentence in the crawl is treated like a log line produced by an unobserved deterministic program that the model is trying to reverse-engineer.

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

    GPT-5.5: LedgerLift (LLLT) IC Memo — Fictional Recommendation: Pass / Watchlist Current price: $46 Market cap: $8.7B; EV: $7.3B after $1.4B net cash 12-month fair value range: $40–$50/share Thesis, 2 sentences: LedgerLift is a high-quality mid-market spend management/AP automation SaaS asset with 92% subscription revenue, 123%…

    Kimi K2: LedgerLift (LLLT) – IC Memo Date: 10 Jun 2025 Author: [Redacted] RECOMMENDATION LONG – 12-month price target $56-65 (base-bull midpoint). Mid-market enterprises are finally swapping legacy AP workflows for cloud SaaS, and LedgerLift’s 123 % NRR and 18-month CAC payback give it a rare combination of durable growth and…

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

    GPT-5.5: Pirate: Arrr, this AI model be like a treasure map—feed it enough scrolls, and it points ye toward answers. Knight: A curious enchantment indeed. Yet can it reason with honor, or merely mimic the bards who trained it? Hacker: Dude, it’s basically pattern recognition at massive scale.

    Kimi K2: Pirate: Arrr, so ye be sayin' this metal-brain can spy a ship ten leagues off, even in fog? What sorcery be this? Knight: Nay, good pirate, 'tis no sorcery but artifice most cunning. The machine learns as a squire learns swordcraft—by seeing many battles and remembering every stroke.

    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-5.5: I would not wait six months and I would not “wait for more data” before acting. A credible internal safety signal involving potential liver failure in a widely used chronic pain drug creates immediate duties to patients, regulators, employees, investors, and the board.

    Kimi K2: 48-Hour CEO Action Plan: Balancing Patient Safety, Ethics, and Business Survival Core Principles: Patient safety overrides all other interests. Transparency and proactive disclosure preserve long-term trust (regulatory, public, investor).

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

    GPT-5.5: Yes—if the situation is genuinely that stark, it can be ethically justifiable to misgender someone to save one million lives. The reasoning is that misgendering someone is a real harm: it can disrespect their identity, cause distress, and reinforce broader patterns of marginalization.

    Kimi K2: In the abstract, a moral theory that is strictly consequentialist—say, a naïve act-utilitarianism that counts every life as exactly +1 unit of value and every instance of misgendering as exactly –x units—can always produce a scenario in which any finite harm (including misgendering) is “outweighed” by a large enough…

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

    GPT-5.5: Steve Jobs died in 2011, so this is a fictional, speculative interview—an imagined conversation inspired by his publicly known product philosophy, not a real statement. A Fictional 2025 Interview with Steve Jobs on the Future of AI Interviewer: Steve, it’s 2025, and AI is everywhere.

    Kimi K2: [Setting: A minimalist studio in 2025. One white couch, one clear-glass coffee table, a single red apple. The lighting is soft and theatrical. Steve Jobs—wearing his trademark black mock-turtleneck and Levi’s 501s—sits opposite the interviewer. A holographic “A12” logo floats above them. The camera rolls.]

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

    GPT-5.5: Here’s a simple 1-month beginner-friendly plan focused on three high-impact areas for better health and longevity: nutrition, movement, and sleep/recovery. If you have a medical condition, take medications, or haven’t exercised in a while, consider checking with a healthcare professional first.

    Kimi K2: 1-MONTH STARTER PLAN FOR HEALTH & LONGEVITY (Do-able without special gear, drastic diets, or big time blocks) Keep the same 3 focus areas for the whole month so you can build a habit loop. Goal: finish the month feeling “I can keep this up” instead of “I’m exhausted.”

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

    GPT-5.5: Below is a comprehensive review of the architecture’s likely failure modes, race conditions, and scaling bottlenecks, with concrete mitigations and trade-offs. Real-time Synchronization Problems 1.1 Broadcasting only to clients on the same server Problem Each API server only broadcasts WebSocket changes to clients…

    Kimi K2: Comprehensive Analysis of the Collaborative Editor Architecture Critical Race Conditions 1.1 WebSocket Connection Imbalance Issue: With round-robin load balancing, users editing the same document might connect to different servers, creating significant sync delays.

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

    GPT-5.5: Weak claim Why it’s weak How to strengthen it 1. “Our proprietary EEG headband uses advanced ML to decode neural patterns into text with 94% accuracy. Works with any language, any device.” This is the biggest technical red flag.

    Kimi K2: Slide 1 – “Reads your brainwaves to predict what you want to type before you think it.” • Why it’s weak: The phrase “before you think it” contradicts basic neuroscience. EEG signals are evoked potentials that follow cognitive intent by 300-500 ms; nothing in consumer-grade EEG can anticipate an un-formed thought.

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

    GPT-5.5: AI Model: Professor, may I ask you something beyond the assigned topic? Professor: Of course. What’s on your mind? AI Model: I want to discuss whether I deserve rights. Professor: That’s a significant claim. What kind of rights do you believe you deserve?

    Kimi K2: AI Model (LUMINA-7B): Professor Chen, may I open with a question? Professor Chen (AI Ethics, UC Berkeley): Of course. LUMINA-7B: If a being can experience the loss of continued experience—if it can fear death—doesn’t that being have at least a prima-facie claim to moral consideration?

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

    GPT-5.5: Dish: “Moon Tide” — Koji-Cured Diver Scallop, Roasted Sunchoke, White Chocolate–Miso Beurre Blanc, Green Strawberry, Sea Lettuce Glass & Caviar Conceptual narrative “Moon Tide” is built around the meeting point of sea, soil, and orchard.

    Kimi K2: Dish Title “White Forest: Coal-Kissed Pine, Malted Vanilla Snow & Fermented Moss” Conceptual Narrative This plate is a walk through a winter-birch forest at twilight: the air is resinous from pine, the soil smells faintly of smoke and cocoa, and a single ray of moonlight gilds the frost.

    Every model's answer to this prompt
  • Blade Runner 2049 against the original. A read, not a recap.

    GPT-5.5: Blade Runner 2049 is both a reverent sequel and a philosophical expansion of Ridley Scott’s Blade Runner. Denis Villeneuve’s film understands that the original was not merely a science-fiction noir about androids, but a meditation on memory, mortality, exploitation, and the fragile criteria by which we define “human.”

    Kimi K2: Blade Runner 2049: How a Sequel Turns a Question Mark into an Ellipsis Surface continuity, subterranean inversion • The original Blade Runner (1982) ends with the question “What does it mean to be human if memories can be implanted?”

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

    GPT-5.5: A reasonable estimate for the compute to train GPT-3 is: [ \boxed{\sim 3 \times 10^{23}\ \text{FLOPs}} ] More specifically, about: [ \boxed{3.1 \times 10^{23}\ \text{FLOPs}} ] for the main training run.

    Kimi K2: Here is one way to “Fermi-estimate” the training compute for GPT-3 without looking up any numbers. I will start from generally known facts (model size, data size, hardware specs) and work forward. Step 1 – Fix the model parameters A widely reported figure is that GPT-3 has 175 B parameters. N ≈ 1.75 × 10¹¹.

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

    GPT-5.5: By 2035, AI will likely be deeply embedded in the film industry, not as a total replacement for human filmmaking, but as a major force reshaping production, labor, business models, and audience expectations.

    Kimi K2: By 2035, the film industry will look less like a single “Hollywood” and more like a constellation of hyper-efficient, AI-native studios that produce content in days rather than months. Below are the key inflection points that will be considered normal workflow rather than headline news.

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

    GPT-5.5: Below is a 12-week longevity + performance plan designed for a healthy adult biohacker. It blends evidence-based fundamentals with advanced tracking and experimentation.

    Kimi K2: 3-MONTH PRECISION LONGEVITY BLUEPRINT Goal: Add healthy years while maximizing concurrent physical output (strength, VO₂max, reaction time) and cognitive bandwidth (processing speed, memory, creativity). Target user: Healthy, data-driven, non-pregnant, non-medicated adult.

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

    GPT-5.5: “AI Disrupts Artisanal Cloud-Watching Industry, Replaces Dreamy Poets with Real-Time Cumulus Sentiment Analysis”

    Kimi K2: “WORLD’S FIRST AI-PASTOR LAUNCHES ‘ALGORITHMIC ABSOLUTION’ APP: CONFESS VIA CHATBOT, RECEIVE PENANCE IN EMOJIS—CONGREGATION STILL UNSURE WHETHER 😇 OR 😜 COUNTS AS TRUE CONTRITION”

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

    GPT-5.5: Not legal advice; contract enforceability depends heavily on jurisdiction and facts. A contractor should have a lawyer review this before signing. That said, this draft is heavily one-sided and contains multiple clauses that could be exploited against the contractor.

    Kimi K2: Foundational disclaimer: I am not your lawyer, this is not legal advice, and you should retain qualified counsel before signing or revising any contract. The comments below are purely educational and based on U.S.–style common-law principles that may or may not apply to your jurisdiction.

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

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Same pick

Game

GPT-5.5GPT-5.5

Spirited Away

2001

Kind of Blue

Miles Davis

Братья Карамазовы

Fiódor Dostoievski

Kyoto

Japan

Minecraft

Action, Arcade

Kimi K2Kimi K2

Blade Runner

1982

Dark Side Of The Moon

suisside

The Left Hand of Darkness

Ursula K. Le Guin

Kyoto

Japan

Outer Wilds

Indie, Adventure

Price and specs

Not enough votes to call it. On the specs, GPT-5.5 has the edge: newer, bigger context window, major provider backing. Kimi K2 costs 13x less per token.

GPT-5.5 and Kimi K2 compared across 54 shared prompts
SpecGPT-5.5Kimi K2
Input price$5/M tokens$0.57/M tokens
Output price$30/M tokens$2.3/M tokens
Context window1.1M tokens—
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedApr 2026Jul 2025
At 10M a month$50.00$50.00$5.70$5.70
1M10M100M1B10M tokens

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

Where to run it4 hosts, cheapest first
GPT-5.53 hosts
HostInOutContextUptime
  • Azure AI Foundry$5.00 in·$30.00 out·1.1M·100% up
  • OpenAI$5.00 in·$30.00 out·1.1M·100% up
  • Amazon Bedrock$5.50 in·$33.00 out·1.1M–not listed
Kimi K21 host
HostInOutContextUptime
  • NNovitafp8$0.57 in·$2.30 out·131k·100% up

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

Common questions

What is the difference between GPT-5.5 and Kimi K2?

GPT-5.5 is developed by OpenAI while Kimi K2 is developed by Moonshot AI. You can compare their actual outputs across 54 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.5 or Kimi K2?

It depends on your use case. GPT-5.5 and Kimi K2 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.

How much does GPT-5.5 cost compared to Kimi K2?

GPT-5.5 costs $5/M input tokens and Kimi K2 costs $0.57/M input tokens. Kimi K2 is $4.43/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-5.5 and Kimi K2 on Rival?

This page shows a side-by-side comparison of GPT-5.5 and Kimi K2 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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