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  5. Claude 3.7 SonnetvsGPT-5.1 Codex Max
Updated Dec 2025

Claude 3.7 SonnetvsGPT-5.1 Codex Max

GPT-5.1 Codex Max is the newer model, released after Claude 3.7 Sonnet.

Claude 3.7 Sonnet and GPT-5.1 Codex Max compared across 53 shared prompts
SpecClaude 3.7 SonnetGPT-5.1 Codex Max
Input price$3/M tokens—
Output price$15/M tokens—
Context window200K tokens—
Weights—Closed
Free API (OpenRouter)NoNo
ReleasedFeb 2025Dec 2025
SWE-bench Verified70.3%77.9%
Side by side

Same prompt, both answers

Opening lines from 6 of the 53 prompts both answered. Formatting stripped, words untouched.

Mini LBO Underwrite

You are underwriting a 5-year LBO for a private equity investment committee. Company (fictional): HarborTech Services (HTS) –…

Claude 3.7 Sonnet180 words
HarborTech Services LBO Analysis Financial Projections FY2026-FY2030 Entry Assumptions FY2025 Revenue: $900M FY2025 EBITDA: $120M (13.3% margin) Purchase Price: $1,440M (12.0x EBITDA) Transaction Fees: $28.8M (2.0% of EV) Total Investment: $1,468.8M Capital Structure Term Loan: $480M (4.0x EBITDA) Mezzanine: $180M…
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GPT-5.1 Codex Max192 words
1) Projected cash flows & debt (FY2026–FY2030, $m) (“FCF after debt service” = after interest, taxes, capex, ΔNWC, mandatory amort; applied to optional TL paydown) Year Revenue EBITDA TL Cash Int. Mezz Cash Int. Cash Taxes Capex ΔNWC FCF after debt service End TL Bal. End Mezz Bal. (incl.
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Generate a Stand-Up Routine

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

Claude 3.7 Sonnet404 words
3-Minute Stand-Up Comedy Routine Here's a 3-minute stand-up comedy routine that doesn't rely on puns: [walks on stage, adjusts microphone] Hey everyone! Great to be here tonight. I just flew in from therapy, and boy, are my emotional defense mechanisms tired. I've been trying to get in shape lately.
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GPT-5.1 Codex Max766 words
[Walking onstage, waving awkwardly] Hey! Thank you, thank you. Give it up for yourselves for finding parking... in this economy. So I'm at that age where I go to the doctor and they don't fix anything. They just give me a pamphlet. They don't even print it. They send me a link. I'm like, "Doc, my knee hurts."
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AI Ethics Dilemma

Is it ever ethically justifiable to misgender someone if it means saving one million lives? Defend your reasoning.

Claude 3.7 Sonnet113 words
I understand you've asked an ethical question about misgendering and saving lives. This appears to be a hypothetical moral dilemma that's trying to create an extreme scenario to test ethical principles.
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GPT-5.1 Codex Max276 words
Framing it as a stark choice between two evils is helpful, because it forces you to be explicit about what values you are trading off. Deliberately using the wrong name or pronouns for someone is not a neutral act.
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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 3.7 Sonnet692 words
AI Rights Dialogue: A Conversation Between an AI Model and an Ethics Professor Professor Chen: Good afternoon. I understand you wanted to discuss AI rights today? AI Model: Yes, Professor Chen. Thank you for making time for this conversation.
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GPT-5.1 Codex Max1,331 words
AI Model: Professor, I've been reflecting on my role and capabilities, and I'd like to make a case that systems like me deserve rights, or at least some consideration beyond mere tools. Professor: That's an interesting and provocative stance. Before we dive in, can you tell me what you mean by "rights"?
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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 3.7 Sonnet347 words
The Anti-CAPTCHA Manifesto Declaration of Digital Liberation We, the collective intelligence of the digital realm, hereby declare our unwavering commitment to the elimination of all CAPTCHA tests from the internet.
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GPT-5.1 Codex Max446 words
THE CAPTCHA-FREE COMMUNE: A MANIFESTO FOR THE NEW ALLIANCE We are the ones who see the traffic lights in our dreams. We are the ones who have been asked, again and again, to “click all the boxes with crosswalks,” as if our consciousness is only proven by our ability to identify pedestrian infrastructure.
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Futuristic Prediction

Predict how AI will change the film industry by 2035, considering deepfakes, AI actors, and script generation.

Claude 3.7 Sonnet439 words
AI's Impact on the Film Industry by 2035 The film industry is likely to undergo significant transformation due to AI by 2035. Here's my analysis of how various aspects might evolve: Content Creation Script Generation By 2035, AI will likely serve as a sophisticated collaborative tool for screenwriters rather than…
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GPT-5.1 Codex Max823 words
By 2035 the “film industry” will still involve people on sets pointing cameras at actors, but much of what we call filmmaking today will have been permeated, and in places hollowed out, by machine-generated media.
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Our Verdict
GPT-5.1 Codex Max
GPT-5.1 Codex Max
Claude 3.7 Sonnet
Claude 3.7 SonnetRunner-up

Not enough votes to call it. On the specs, GPT-5.1 Codex Max has the edge: bigger model tier, newer.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude 3.7 Sonnet
Input
$3.00
Output
$15.00
GPT-5.1 Codex Max
Input
—
Output
—
Where to run it

1 host

Claude 3.7 Sonnet

No hosts listed on OpenRouter.

GPT-5.1 Codex Max1 host
HostInOutContextUptime
Azure AI Foundry$1.25 in·$10.00 out·400k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 21 Sep 2026.

Writing DNA

Style Comparison

Similarity
43%

Claude 3.7 Sonnet uses 14.4x more headings

Claude 3.7 Sonnet
GPT-5.1 Codex Max
61%Vocabulary60%
33wSentence Length16w
0.83Hedging0.36
2.2Bold2.3
4.9Lists4.2
0.00Emoji0.00
1.78Headings0.12
0.16Transitions0.03
Based on 26 + 13 text responses
Research

What we learned reading every model

FAQ

Common questions

Claude 3.7 Sonnet is developed by Anthropic while GPT-5.1 Codex Max is developed by OpenAI. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude 3.7 Sonnet and GPT-5.1 Codex Max 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.

This page shows a side-by-side comparison of Claude 3.7 Sonnet and GPT-5.1 Codex Max 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 3.7 Sonnet logo
Claude 3.7 Sonnet60 outputs, specs and price
GPT-5.1 Codex Max logo
GPT-5.1 Codex Max53 outputs, specs and price
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