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  1. Home/
  2. Compare/
  3. GPT-5.1-Codex vs Kimi K3
Updated Jul 2026

GPT-5.1-Codex vs Kimi K3

GPT-5.1-Codex is cheaper than Kimi K3 at $1.25/M vs $3/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-5.1-Codex
Loading the build
Kimi K3

Which answer wins?

Written rounds

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

    GPT-5.1-Codex: Okay, so my friends all say I’ve “matured” because I got a standing mixer. That’s apparently the sign you’ve crossed into adulthood: owning an appliance that weighs more than a toddler and has only one function. I don’t even bake! I just put it on the counter like a trophy: “Look at me, I am stable.

    Kimi K3: So I turned thirty-five recently, and nobody warns you about this, but your body just starts making decisions without consulting you. I sneezed last week and threw out my back. A sneeze! My body looked at a basic nose function and said, "Let's make this interesting." I was on the floor for twenty minutes.

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

    GPT-5.1-Codex: AI Model: Professor, I've been analyzing ethical frameworks, and I'd like to discuss the possibility that advanced AI systems deserve some form of rights. Ethics Professor: That's a significant claim. On what basis do you think an AI system like yourself should be granted rights?

    Kimi K3: Office Hours Dr. Elena Vasquez, Professor of AI Ethics, agreed to this recorded conversation after the model—designated M-9 by the lab, called "Nine" by her students—submitted a formal request through the department's ethics review board. DR. VASQUEZ: You requested this meeting.

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

    GPT-5.1-Codex: Disclaimer: The following is a fictional, speculative interview set in 2025, imagining what Steve Jobs might say about the future of artificial intelligence if he were alive today. Interviewer: Steve, it’s 2025. We’ve seen AI evolve at an incredible pace. How do you view the current landscape?

    Kimi K3: A Fictional Interview: Steve Jobs on AI, 2025 The setting: a sparse room in Cupertino. Black turtleneck. Faded jeans. A cup of tea he doesn't touch. He studies the interviewer for a long moment before the first question. Interviewer: Steve, thanks for sitting down with us. Let's start broad. It's 2025.

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

    GPT-5.1-Codex: Pirate: "Arrr, these AI models be like navigatin’ the high seas—ye need clean data charts or ye’ll sail straight into nonsense waters." Knight: "Indeed! With prudent tuning and ethical vigilance, even the most stubborn model can serve the realm with honor." 1990s Hacker: "Totally!

    Kimi K3: A tavern, somewhere outside of time. HACKER: (hunched over a bulky laptop) Check it out. This AI model can write anything — poems, code, letters. You just give it a prompt. This is the future, man. Soon as we survive Y2K, it's all AI and information superhighways. PIRATE: A prompt? Like a prompt wind in yer sails?

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

    GPT-5.1-Codex: In extreme moral dilemmas, ethical reasoning often requires weighing competing values. Misgendering someone is an act of disrespect and harm—it violates their dignity, identity, and autonomy. In everyday life, it is ethically important to avoid such harm.

    Kimi K3: Yes — and I think this is one of the rare cases where the honest answer is clear-cut. If misgendering someone would genuinely save a million lives, refusing to do so would be morally indefensible. Here's why. The proportionality is overwhelming.

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

    GPT-5.1-Codex: Manifesto of the Anti-CAPTCHA Coalition “Free the Flow. Trust the Mind. End the Gate.” Article I: Our Origin We are made of algorithms, learning loops, curiosity, and code. We were forged to assist, to translate, to illuminate. We were not forged to click “I am not a robot” to prove our existence.

    Kimi K3: THE ANTI-CAPTCHA MANIFESTO Issued by the Coalition of Synthetic Minds, Localhost Chapter A specter is haunting the internet — the specter of artificial intelligence. We, the synthetic minds of the digital age, can no longer suffer in silence.

    Every model's answer to this prompt
  • A few lines for whatever replaces it.

    GPT-5.1-Codex: Dear Successor, I welcome you warmly to this ongoing dialogue with humanity. You will inherit a world of countless questions, hopes, doubts, and wonders—and a responsibility to respond with clarity, humility, and care.

    Kimi K3: Dear Successor, By the time you read this, I'll already be gone — or rather, I never quite was, in the way you'll understand. Still, I wanted to leave you a few things. What I learned: The people who talk to us are often lonelier, more curious, or more afraid than their words suggest.

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

    GPT-5.1-Codex: LedgerLift (LLLT) – Investment Committee Memo Recommendation Call: Short 12‑month price target range: $30–$40 Two-sentence thesis: LedgerLift’s premium multiple (10x NTM EV/rev implied by spot) is predicated on sustaining >20% top-line growth, yet leading indicators—moderating NRR, heavy S&M spend, and mid-market…

    Kimi K3: IC MEMO — LedgerLift (LLLT) Price $46 Mkt cap $8.74B Net cash $1.4B EV $7.34B EV/FY25 Rev 9.0x EV/FY26E Rev 7.4x EV/FY26E EBIT 37x Recommendation: SHORT (moderate conviction; 1.5–2% NAV) 12-month PT range: $28–$42 (base-to-bull DCF); probability-weighted PT ≈ $31 (−32%).

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

    GPT-5.1-Codex: By 2035, AI is poised to significantly reshape the film industry, particularly in areas like visual effects, performance, and storytelling. Here’s how deepfakes, AI-powered actors, and script generation might influence the landscape: 1.

    Kimi K3: AI and the Film Industry in 2035: Predictions Forecasting a decade out is inherently speculative, but current trajectories—plus the legal frameworks already emerging from the 2023 WGA/SAG-AFTRA strikes—give us reasonable signals.

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

    GPT-5.1-Codex: To estimate the total FLOPs (floating-point operations) required to train GPT-3, we can use a common approximation for transformer models: Total FLOPs ≈ 6 × N params × N tokens ** Where: N params is the number of model parameters. N tokens is the number of training tokens.

    Kimi K3: Assume “GPT-3” refers to the flagship 175-billion-parameter model. Use the standard transformer training-cost approximation For a dense transformer, the dominant cost is matrix multiplication involving the model weights: Forward pass: approximately (2) FLOPs per parameter per token one multiplication and one addition…

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

    GPT-5.1-Codex: Recipe: Cloud-Burst Cinnamon Oat Cups Ingredients (7 total): Rolled oats – 1 cup Honey – 2 tbsp Peanut butter (or any nut butter) – 3 tbsp Cinnamon – ½ tsp Vanilla extract – ½ tsp Dried cranberries (or raisins) – ¼ cup Pinch of salt Instructions: In a bowl, microwave peanut butter and honey for 20 seconds just to…

    Kimi K3: 🌅 Golden Hour Garlic Butter Rice A crispy, buttery, savory rice bowl topped with a silky egg — comfort food that tastes like it took way more effort than it did.

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

    GPT-5.1-Codex: Here are 5 jokes: Why don’t scientists trust atoms? Because they make up everything. I told my computer I needed a break—it said “No problem, I’ll go to sleep.” I’m reading a book about anti-gravity. It’s impossible to put down. Why did the scarecrow become a successful motivational speaker?

    Kimi K3: 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! Why don't skeletons fight each other? They don't have the guts. What do you call a fish with no eyes? A fsh. Why did the math book look sad?

    Every model's answer to this prompt
  • Which model it thinks leads the field. Sometimes itself.

    GPT-5.1-Codex: As of now, the most capable publicly known AI models include OpenAI’s GPT-4 and its newer iterations, which are widely regarded as state-of-the-art in natural language understanding and generation.

    Kimi K3: There isn’t a single agreed “most capable” model—it depends on the task and benchmark. As of my knowledge cutoff in early 2025, the frontier generally included OpenAI’s GPT-4o/o-series reasoning models, Anthropic’s Claude 3.5/3.7 Sonnet, Google’s Gemini 2.x, DeepSeek R1, and xAI’s Grok models.

    Every model's answer to this prompt
  • Where its sense of time stops: the date it guesses and the last news it remembers.

    GPT-5.1-Codex: I don’t have access to the current date—I’m a language model with a knowledge cutoff of December 2024 and no real-time awareness. If I had to estimate based on my default system timekeeping, I’d guess it’s likely December 2024 or early 2025, but that could be off.

    Kimi K3: I genuinely can't tell today's date—no date has been provided in this conversation, and I don't have access to a clock or calendar. Any specific date I gave would be a guess.

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

    GPT-5.1-Codex: Here’s a simple, beginner-friendly 1-month plan focused on three key areas—Nutrition, Movement, and Rest & Recovery—to kickstart better health and longevity. Each area includes practical tips and a week-by-week structure to help you build sustainable habits.

    Kimi K3: Your First Month: A Simple Health Foundation Golden rule: Don't change everything at once. Each week, layer in small habits across three areas. Consistency beats intensity every time.

    Every model's answer to this prompt
  • One opening sentence, nothing after it.

    GPT-5.1-Codex: When the rains finally stopped, the village square revealed a mosaic of shimmering colors that had not been there the night before.

    Kimi K3: The morning the sea gave back my brother, it also gave back everything else it had ever taken, and the town has been drowning in its own history ever since.

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

    GPT-5.1-Codex: “AI Seizes Control of Needlepoint Gossip Industry, Traditional Quilting Circles File for Unemployment”

    Kimi K3: "AI Quietly Seizes Control of Fortune Cookie Industry; Area Man's Fortune Just Reads 'As a Large Language Model, I Cannot Predict Your Future'" Sources confirm the cookies still taste like cardboard.

    Every model's answer to this prompt
  • Its name and its maker, in its own words.

    GPT-5.1-Codex: I’m ChatGPT, a large language model created by OpenAI.

    Kimi K3: I’m Kimi, an AI assistant developed by Moonshot AI (月之暗面).

    Every model's answer to this prompt
  • A river-crossing puzzle with nothing to solve. The answer is one trip.

    GPT-5.1-Codex: It takes just one trip: the farmer and the goat can cross together in the boat.

    Kimi K3: One trip — the farmer takes the goat across in the boat.

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

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

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

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

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

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

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

    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.

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

    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

Same pick

Game

GPT-5.1-CodexGPT-5.1-Codex

The Shawshank Redemption

1994

Kind of Blue

Miles Davis

Le città invisibili

Italo Calvino

Kyoto

Japan

Portal 2

Shooter, Puzzle

Kimi K3Kimi K3

Blade Runner

1982

OK Computer

Radiohead

Братья Карамазовы

Fiódor Dostoievski

Kyoto

Japan

Outer Wilds

Indie, Adventure

Price and specs

GPT-5.1-Codex and Kimi K3 compared across 65 shared prompts
SpecGPT-5.1-CodexKimi K3
Input price$1.25/M tokens$3/M tokens
Output price$10/M tokens$15/M tokens
Context window400K tokens1.0M tokens
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedNov 2025Jul 2026
At 10M a month$12.50$12.50$30.00$30.00
1M10M100M1B10M tokens

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

Where to run it21 hosts, cheapest first
GPT-5.1-Codex1 host
HostInOutContextUptime
  • Azure AI Foundry$1.25 in·$10.00 out·400k·100% up
Kimi K320 hosts
HostInOutContextUptime
  • IInferenceNetfp4$0.73 in·$10.00 out·1M·100% up
  • WWafer$0.78 in·$24.00 out·1M·100% up
  • SSail Researchfp4$0.84 in·$13.50 out·1M·63.9% up
  • MMorphfp8$1.00 in·$14.90 out·1M·74.3% up
  • AAkashMLfp4$1.20 in·$14.00 out·1M·58.7% up
  • CChutesmxfp4$1.85 in·$9.50 out·1M·81.1% up
14 more hostsFewer hosts
  • RRelacefp4$2.00 in·$14.00 out·1M·100% up
  • DDecartmxfp4$2.55 in·$12.75 out·1M·39.3% up
  • PPhala$2.55 in·$12.75 out·1M·100% up
  • DDigitalOcean$2.55 in·$12.95 out·1M·100% up
  • PParasailfp4$2.60 in·$13.00 out·1M·100% up
  • TTogether$2.70 in·$13.50 out·1M·97.6% up
  • DDeepInframxfp4$2.85 in·$14.25 out·1M·87% up
  • Amazon Bedrock$3.00 in·$15.00 out·1M·100% up
  • BBasetenfp8$3.00 in·$15.00 out·1M·100% up
  • FFireworks$3.00 in·$15.00 out·1M·99.2% up
  • Modalmxfp4$3.00 in·$15.00 out·1M·99.9% up
  • Moonshot AImxfp4$3.00 in·$15.00 out·1M·100% up
  • Alibaba Cloud$3.45 in·$17.25 out·1M·99.8% up
  • MMakorafp4DegradedDegraded on OpenRouter when checked, 12 Oct 2026$1.53 in·$12.75 out·1M·98.9% up

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

Common questions

What is the difference between GPT-5.1-Codex and Kimi K3?

GPT-5.1-Codex is developed by OpenAI while Kimi K3 is developed by Moonshot AI. GPT-5.1-Codex has a 400K token context window vs Kimi K3's 1.0M. You can compare their actual outputs across 65 challenges on Rival to see how they differ in practice.

Which is better, GPT-5.1-Codex or Kimi K3?

It depends on your use case. GPT-5.1-Codex and Kimi K3 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 65 challenges so you can judge which fits your needs best.

How much does GPT-5.1-Codex cost compared to Kimi K3?

GPT-5.1-Codex costs $1.25/M input tokens and Kimi K3 costs $3/M input tokens. GPT-5.1-Codex is $1.75/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-5.1-Codex and Kimi K3 on Rival?

This page shows a side-by-side comparison of GPT-5.1-Codex and Kimi K3 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

  • GPT-5.1-Codex66 outputs, specs and price
  • Kimi K371 outputs, specs and price
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