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  5. Claude Opus 5.5vsNemotron 3 Ultra
Updated Sep 2026

Claude Opus 5.5vsNemotron 3 Ultra

Nemotron 3 Ultra is cheaper than Claude Opus 5.5 at $0/M vs $4/M input tokens.

Claude Opus 5.5 and Nemotron 3 Ultra compared across 19 shared prompts
SpecClaude Opus 5.5Nemotron 3 Ultra
Input price$4/M tokensFree
Output price$20/M tokensFree
Context window1.0M tokens1.0M tokens
WeightsClosedOpen
Free API (OpenRouter)NoYes (1 provider)
ReleasedSep 2026Jun 2026
Side by side

Same prompt, both answers

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

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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Nemotron 3 Ultra1,516 words
Dish Title: Petrichor: The Memory of Dry Earth Meeting Rain Classification: Amuse-Bouche / Palate Awakener (Serves 1, scaled for service of 12) Conceptual Tier: Michelin 3-Star (Technique: Ultra-high precision, multi-sensory engagement, molecular architecture, zero-waste philosophy) I.
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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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Nemotron 3 Ultra1,810 words
This is a profound "hard takeoff" scenario. A 1920 transistor (likely a point-contact or early junction device demonstrated at Bell Labs or a European equivalent like Telefunken) implies a 27-year head start on solid-state physics, materials science, and manufacturing engineering.
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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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Nemotron 3 Ultra1,165 words
Disclaimer: I am not a licensed attorney. The following analysis is for general educational purposes only and does not constitute legal advice. Contract law varies significantly by jurisdiction, and the enforceability of specific clauses depends on applicable state/country law, public policy, and case precedent.
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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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Nemotron 3 Ultra1,607 words
Architecture Analysis: Real-Time Collaborative Editor Critical Failure Modes Client-Side Timestamps for Conflict Resolution Problem: Last-write-wins uses client clocks. Clocks drift (NTP sync issues), users change system time, timezone bugs. Two simultaneous edits → arbitrary winner based on broken clocks.
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Explain Like I'm a Specific Expert

Explain how a large language model (like GPT or Claude) learns and generates text to each of these three audiences: 1. **An experienced…

Claude Opus 5.51,442 words
How Large Language Models Work: Three Explanations For the Experienced Software Engineer Think of an LLM as a single, very large pure function: f(tokens[0..n]) → probability distribution over tokens[n+1]. Text is chunked into tokens (roughly word fragments, from a vocabulary of about 100k).
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Nemotron 3 Ultra1,049 words
For the Experienced Software Engineer Think of an LLM as a massively parallel, differentiable database where the "schema" is learned rather than designed. The transformer architecture is essentially a stack of attention blocks that route information across token positions — each block is a small, fixed computation…
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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 $4.8m per year. Mezz PIK accrues to principal. All FCF after mandatory debt service sweeps to the TL.
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Nemotron 3 Ultra685 words
HarborTech Services (HTS) – 5-Year LBO Underwriting 1. Sources & Uses (Close FY2025) Uses Amount ($m) Sources Amount ($m) x EBITDA Enterprise Value (12.0x) 1,440.0 Term Loan (9% cash, 1% amort) 480.0 4.0x Transaction Fees (2.0%) 28.8 Mezzanine (12% cash + 2% PIK) 180.0 1.5x Total Uses 1,468.8 Equity 808.8 5.5x Total…
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Our Verdict
Claude Opus 5.5
Claude Opus 5.5
Nemotron 3 Ultra
Nemotron 3 Ultra

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

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
Nemotron 3 Ultra
Input
$0.000
Output
$0.000
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
Nemotron 3 Ultra1 host
HostInOutContextUptime
NVIDIA$0 in·$0 out·1M·98.8% 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 Nemotron 3 Ultra is developed by NVIDIA. Claude Opus 5.5 has a 1.0M token context window vs Nemotron 3 Ultra'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 Nemotron 3 Ultra 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 Nemotron 3 Ultra costs $0/M input tokens. Nemotron 3 Ultra is $4.00/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 Nemotron 3 Ultra 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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