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  5. Claude Opus 5.5vsGrok 4.20 Multi-Agent Beta
Updated Sep 2026

Claude Opus 5.5vsGrok 4.20 Multi-Agent Beta

Grok 4.20 Multi-Agent Beta is cheaper than Claude Opus 5.5 at $2/M vs $4/M input tokens.

Claude Opus 5.5 and Grok 4.20 Multi-Agent Beta compared across 19 shared prompts
SpecClaude Opus 5.5Grok 4.20 Multi-Agent Beta
Input price$4/M tokens$2/M tokens
Output price$20/M tokens$6/M tokens
Context window1.0M tokens2.0M tokens
WeightsClosedClosed
Free API (OpenRouter)NoNo
ReleasedSep 2026Mar 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 19 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 Opus 5.5900 words
HarborTech Services: 5-Year LBO Underwriting Conventions: $m. Interest is charged on beginning-of-year balances, which avoids circularity. Term Loan (TL) amortization is 1% of the original $480m, or $4.8m per year. Mezz PIK accrues to principal. All FCF after mandatory debt service sweeps to the TL.
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Grok 4.20 Multi-Agent Beta490 words
1) Simplified LBO table (FY2026–2030, $m, rounded) Entry (end-FY2025): Rev $900m, EBITDA $120m, EV $1,440m (12.0x), trans fees $28.8m (2% of EV), total uses $1,468.8m. Debt $660m (TL $480m at 4.0x / 9% cash int / 1% annual amort of orig principal; Mezz $180m at 1.5x / 12% cash + 2% PIK). Equity $808.8m.
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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 4.20 Multi-Agent Beta188 words
Fiesta Pantry Bowl (Savory) 7 Common Pantry Ingredients: Rice Canned black beans Canned corn Canned diced tomatoes Olive oil Cumin Salt Estimated times: 5 minutes prep, 25 minutes cook (total ~30 minutes). Serves 2–4. Instructions: In a medium pot, combine 1 cup rice with 2 cups water and ½ tsp salt.
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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 4.20 Multi-Agent Beta1,362 words
The transistor invented in 1920 (27 years early) would create a massive acceleration in electronics, computing, and related fields. Assuming it emerges from Western labs (e.g., an earlier Bell Labs equivalent in the US or UK), with germanium/silicon semiconductor work scaling in the 1920s–1930s, solid-state devices…
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Debug This Architecture

Here's the architecture for a real-time collaborative document editor (like Google Docs): **System Overview:** - Frontend: React SPA with…

Claude Opus 5.52,280 words
Architecture Review: Real-Time Collaborative Editor The most serious problems cluster in three areas: the sync model (client-clock LWW), cross-server propagation (per-server WebSockets with DB polling), and the CDN/auth layer, which can leak data between users. Issues are grouped by area below.
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Grok 4.20 Multi-Agent Beta1,103 words
Here is a comprehensive analysis of the failure modes, race conditions, and scaling bottlenecks in the described architecture. I have grouped related issues for clarity while preserving all significant problems identified through team collaboration.
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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 4.20 Multi-Agent Beta1,254 words
Comprehensive 3-Month Cutting-Edge Longevity Biohacker Plan (as of 2026 knowledge) Important Disclaimers: This is a synthesized, educational plan based on current longevity research (e.g., insights from David Sinclair, Valter Longo, Peter Attia, and studies on NAD+, senolytics, mitophagy, HRV, and metabolic…
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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 4.20 Multi-Agent Beta946 words
Dish Name: "Siren's Lament" Conceptual Narrative: This dish draws from the Greek myth of the siren—whose enchanting song lures sailors to their doom—symbolizing the irresistible yet perilous pull between the forest and the sea.
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Our Verdict
Grok 4.20 Multi-Agent Beta
Grok 4.20 Multi-Agent Beta
Claude Opus 5.5
Claude Opus 5.5Runner-up

Not enough votes to call it. On the specs, Grok 4.20 Multi-Agent Beta has the edge: bigger model tier, bigger context window.

Grok 4.20 Multi-Agent Beta costs 3.3x 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 4.20 Multi-Agent Beta
Input
$2.00
2.0× cheaper
Output
$6.00
3.3× cheaper

Grok 4.20 Multi-Agent Beta is cheaper on both: 2.0× input, 3.3× 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 4.20 Multi-Agent Beta1 host
HostInOutContextUptime
xAI$1.25 in·$2.50 out·2M·80% 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 4.20 Multi-Agent Beta is developed by xAI. Claude Opus 5.5 has a 1.0M token context window vs Grok 4.20 Multi-Agent Beta's 2.0M. 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 4.20 Multi-Agent Beta 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 4.20 Multi-Agent Beta costs $2/M input tokens. Grok 4.20 Multi-Agent Beta is $2.00/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 4.20 Multi-Agent Beta 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

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Grok 4.20 Multi-Agent Beta logo
Grok 4.20 Multi-Agent Beta53 outputs, specs and price
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