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  5. Claude Opus 5.5vsDeepSeek V4 Flash 0731
Updated Sep 2026

Claude Opus 5.5vsDeepSeek V4 Flash 0731

DeepSeek V4 Flash 0731 is cheaper than Claude Opus 5.5 at $0.14/M vs $4/M input tokens.

Claude Opus 5.5 and DeepSeek V4 Flash 0731 compared across 18 shared prompts
SpecClaude Opus 5.5DeepSeek V4 Flash 0731
Input price$4/M tokens$0.14/M tokens
Output price$20/M tokens$0.28/M tokens
Context window1.0M tokens1.0M tokens
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedSep 2026Jul 2026
Side by side

Same prompt, both answers

Opening lines from 6 of the 18 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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DeepSeek V4 Flash 0731287 words
Here is a simple, comforting, and deeply flavorful recipe that comes together in just 20 minutes using only 7 common pantry staples. Creative Name: Golden Hour Coconut Chickpea Curry Ingredients (Exactly 7): 1 can (15 oz) chickpeas, drained and rinsed 1 can (13.5 oz) full-fat coconut milk 1 medium yellow onion 3 cloves…
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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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DeepSeek V4 Flash 0731466 words
Entry / Capitalization FY2025 EBITDA = $120.0m Purchase price = 12.0× $120.0m = $1,440.0m Transaction fees = 2.0% × $1,440.0m = $28.8m Term Loan = 4.0× $120.0m = $480.0m Mezzanine = 1.5× $120.0m = $180.0m Total debt = $660.0m Equity check = $1,440.0m + $28.8m − $660.0m = $808.8m Assumption: Term Loan amortization =…
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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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DeepSeek V4 Flash 07311,492 words
Conceptual Narrative “An Unripe Promise — Hand-Dived Scallop / Green Strawberry / Black Sesame / Celery Root” The dish is an attempt to save a single fleeting moment: the morning a strawberry is still green, sharp, and full of anticipation—before sugar, before ripeness, before memory.
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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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DeepSeek V4 Flash 07311,719 words
Failure Modes, Race Conditions, and Scaling Bottlenecks The described architecture has several critical weaknesses that undermine reliability, consistency, and scalability in a real-time collaborative editor. Below is a systematic analysis with proposed solutions and trade-offs.
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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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DeepSeek V4 Flash 0731748 words
An experienced software engineer Think of the model as a service with one API: predict_next_token(context) -> distribution over vocabulary. During training, you run a gigantic distributed job—shard the corpus, shard the parameters, synchronize gradients—to minimize cross-entropy loss on trillions of tokens.
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Beginner's Longevity Plan

Outline a simple, actionable 1-month plan for someone starting their journey towards better health and longevity. Focus on 3 key areas…

Claude Opus 5.5653 words
Your 1-Month Starter Plan for Better Health & Longevity The philosophy: Small, consistent changes beat dramatic overhauls. Each week builds on the last, so by Day 30 you'll have a foundation of habits instead of a burned-out resolution.
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DeepSeek V4 Flash 0731967 words
Here is a simple, actionable 1-month plan designed for absolute beginners. The goal is consistency over intensity. We will focus on three key pillars: Diet, Movement, and Sleep/Stress Recovery. You don’t need to be perfect—just aim for 80% adherence. If you miss a day, don’t double up tomorrow; just get back on track.
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Our Verdict
Claude Opus 5.5
Claude Opus 5.5
DeepSeek V4 Flash 0731
DeepSeek V4 Flash 0731

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

DeepSeek V4 Flash 0731 costs 71x 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
DeepSeek V4 Flash 0731
Input
$0.14
29× cheaper
Output
$0.28
71× cheaper

DeepSeek V4 Flash 0731 is cheaper on both: 29× input, 71× output.

Where to run it

33 hosts, cheapest first

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
DeepSeek V4 Flash 073129 hosts
HostInOutContextUptime
RRelacefp4$0.03 in·$0.32 out·1M·99.8% upSSail Researchfp4$0.03 in·$0.55 out·1M·99% upSStreamLakefp8$0.05 in·$0.16 out·1M·99.6% upDDeepInfrafp8$0.06 in·$0.18 out·1M·99.8% upWWafer$0.08 in·$0.35 out·1M·100% upIInceptronfp4$0.08 in·$0.41 out·1M·99.8% up
23 more hostsFewer hosts
RReka$0.09 in·$0.53 out·262k·99.8% upMMakora$0.09 in·$0.20 out·1M·98.5% upDDigitalOcean$0.12 in·$0.24 out·1M·100% upBBasetenfp8$0.13 in·$0.26 out·1M·100% upCCoreWeavefp8$0.13 in·$0.28 out·262k·99.9% upPParasailfp8$0.14 in·$0.28 out·1M·99.6% upTTogether$0.14 in·$0.28 out·1M·98% upOOpenInferencefp8$0.14 in·$0.70 out·1M·99.2% upMMorph$0.14 in·$0.40 out·1M·99.2% upVVenice$0.17 in·$0.35 out·1M·99.6% upMMancerfp8$0.20 in·$0.60 out·1M·96% upFFireworks$0.22 in·$0.66 out·1M·98.6% upSSiliconFlowfp8$0.22 in·$0.66 out·1M·99.1% upGGMI Cloudfp8$0.29 in·$0.86 out·1M·99.9% upAlibaba Cloud$0.35 in·$1.06 out·1M·99.8% upNNextBitfp8$0.35 in·$1.06 out·1M·99.9% upNNovitafp8$0.41 in·$1.23 out·1M·100% upAAtlasCloudfp4$0.44 in·$1.32 out·1M·97.6% upBaidu Qianfanfp8$0.44 in·$1.32 out·1M·99.9% upCloudflare Workers AI$0.44 in·$1.32 out·1.3M·100% upPPhala$0.44 in·$1.32 out·1M·99.3% upCoheredegraded$0.14 in·$0.28 out·1M·99.3% upNNebiusfp8degraded$0.14 in·$0.28 out·1M·86.3% 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 DeepSeek V4 Flash 0731 is developed by DeepSeek. Claude Opus 5.5 has a 1.0M token context window vs DeepSeek V4 Flash 0731's 1.0M. You can compare their actual outputs across 18 challenges on Rival to see how they differ in practice.

It depends on your use case. Claude Opus 5.5 and DeepSeek V4 Flash 0731 each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 18 challenges so you can judge which fits your needs best.

Claude Opus 5.5 costs $4/M input tokens and DeepSeek V4 Flash 0731 costs $0.14/M input tokens. DeepSeek V4 Flash 0731 is $3.86/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 DeepSeek V4 Flash 0731 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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DeepSeek V4 Flash 073145 outputs, specs and price
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