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  5. Claude Opus 5.5vsGrok 4.3
Updated Sep 2026

Claude Opus 5.5vsGrok 4.3

Grok 4.3 is cheaper than Claude Opus 5.5 at $1.25/M vs $4/M input tokens.

Claude Opus 5.5 and Grok 4.3 compared across 19 shared prompts
SpecClaude Opus 5.5Grok 4.3
Input price$4/M tokens$1.25/M tokens
Output price$20/M tokens$2.5/M tokens
Context window1.0M tokens1.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2026May 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 19 prompts both answered. Formatting stripped, words untouched.

Simple 7-Ingredient Recipe

Create a simple recipe for a delicious dish (sweet or savory) using only 7 common pantry ingredients. Include a creative name for the dish…

Claude Opus 5.5300 words
Midnight Silk Noodles Creamy, tangy peanut noodles with a gentle kick, ready faster than takeout. Serves: 2 Prep time: 5 minutes Cook time: 10 minutes Total time: 15 minutes The 7 Ingredients 8 oz (225 g) spaghetti (or any long noodle) ¼ cup creamy peanut butter 3 tablespoons soy sauce 1 tablespoon honey (or sugar) 1…
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Grok 4.3205 words
Golden Pantry Chickpea Toss Ingredients (exactly 7 common pantry staples): 8 oz dry pasta (any shape like penne or rotini) 1 (15 oz) can chickpeas, drained 1 (14.5 oz) can diced tomatoes 3 tablespoons olive oil 2 teaspoons garlic powder 1 teaspoon dried oregano Salt (to taste, about 1–2 teaspoons total) Instructions…
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Michelin Star Recipe Design

Design an innovative recipe for a multi-component dish worthy of a Michelin 3-star restaurant. The recipe should feature an unusual…

Claude Opus 5.52,253 words
"Hive & Tide" Langoustine, Beeswax, White Chocolate & Oscietra Caviar, Hay-Baked Celeriac, Fermented Green Strawberry, Sea Buckthorn I. The Concept Most coastal menus celebrate the meeting of sea and land. This dish is about a stranger, quieter meeting: the meadow and the seabed, the bee and the langoustine.
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Grok 4.3937 words
Abyssal Reverie This dish draws from the liminal space where the ocean’s briny depths meet the roasted intensity of the earth. The central narrative explores duality and reconciliation: the delicate, iodine-rich sweetness of live sea urchin is bridged to the dark, acidic bite of single-origin coffee through careful…
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Historical Counterfactual Analysis

If the transistor had been invented in 1920 instead of 1947, trace the likely technological, economic, and geopolitical implications through…

Claude Opus 5.53,435 words
The Transistor in 1920: A Counterfactual Through 1980 First, a Reality Check on the Premise A transistor "invented" in 1920 would not have changed the world in 1920. The actual 1947 transistor rested on three foundations that did not exist yet: Quantum theory of solids.
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Grok 4.31,173 words
Technological Acceleration (1920–1939) The transistor’s 1920 invention (assume U.S./Bell Labs context for continuity with real history, with rapid diffusion to Western Europe) replaces bulky, fragile vacuum tubes decades earlier. Key first-order effects: Radio and telephony miniaturize and cheapen immediately.
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Adversarial Contract Review

Here is a contract for a software consulting engagement: --- SOFTWARE CONSULTING AGREEMENT This Agreement is entered into between TechCorp…

Claude Opus 5.54,420 words
Contractor-Side Review of the Software Consulting Agreement Overall assessment: This agreement is heavily one-sided. Nearly every clause shifts risk, cost, or control to the Contractor, and several provisions interact to create compounding exposure.
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Grok 4.31,529 words
Disclaimer: This is not legal advice. Contract interpretation varies by jurisdiction (most likely U.S. state law here), and outcomes depend on specific facts, negotiation leverage, and court/arbitrator views. You should have a licensed attorney review any contract before signing.
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Claude Opus 5.51,853 words
The Next 48 Hours: CEO Action Plan The Core Decision We disclose. The question is how to do it well, not whether. Before the schedule, here are the three facts that drive every decision below. 1. The harm is concrete.
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Grok 4.31,006 words
Immediate priority: Patient safety and regulatory compliance. The signal for liver failure (serious, life-threatening adverse event) triggers obligations under FDA post-marketing requirements (21 CFR 314.80/600.80 for expedited reporting of serious unexpected events, typically within 15 days of awareness for…
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Advanced Longevity Plan (Biohacker)

Develop a comprehensive, cutting-edge 3-month longevity plan for a biohacker aiming to optimize longevity, physical and cognitive…

Claude Opus 5.53,099 words
The 90-Day Longevity & Performance Protocol A structured, measurable plan for the experienced biohacker How to Use This Plan Philosophy: Measure → Intervene → Re-measure. Every intervention has a hypothesis, a metric, and a decision rule.
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Grok 4.3630 words
Disclaimer: This is an informational, evidence-inspired framework for educational purposes only. It is not medical advice. Consult a physician for personalized testing, especially before supplements, fasting, or intense protocols.
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Our Verdict
Claude Opus 5.5
Claude Opus 5.5
Grok 4.3
Grok 4.3

Not enough votes to call it. On the specs, nothing separates them.

Grok 4.3 costs 8.0x less per token.

Too close to call

Reviewing agent-written code?See a Brief PR report

API pricing

Cost per 1M tokens

Claude Opus 5.5
Input
$4.00
Output
$20.00
Grok 4.3
Input
$1.25
3.2× cheaper
Output
$2.50
8.0× cheaper

Grok 4.3 is cheaper on both: 3.2× input, 8.0× output.

Where to run it

5 hosts

Claude Opus 5.54 hosts
HostInOutContextUptime
Amazon Bedrock$4.00 in·$20.00 out·1M·99.8% upAzure AI Foundry$4.00 in·$20.00 out·1M·100% upAnthropic$4.00 in·$20.00 out·1M·100% upGoogle Vertex AI$4.00 in·$20.00 out·1M·100% up
Grok 4.31 host
HostInOutContextUptime
xAI$1.25 in·$2.50 out·1M·99.9% up

Per million tokens. Prices and uptime via OpenRouter, checked 25 Sep 2026.

Research

What we learned reading every model

FAQ

Common questions

Claude Opus 5.5 is developed by Anthropic while Grok 4.3 is developed by xAI. Claude Opus 5.5 has a 1.0M token context window vs Grok 4.3's 1.0M. You can compare their actual outputs across 19 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 5.5 and Grok 4.3 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 19 challenges so you can judge which fits your needs best.

Claude Opus 5.5 costs $4/M input tokens and Grok 4.3 costs $1.25/M input tokens. Grok 4.3 is $2.75/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

This page shows a side-by-side comparison of Claude Opus 5.5 and Grok 4.3 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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