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  5. Claude Opus 5.5vsSeed 2.0 Code
Updated Sep 2026

Claude Opus 5.5vsSeed 2.0 Code

Seed 2.0 Code is cheaper than Claude Opus 5.5 at $0.5/M vs $4/M input tokens.

Claude Opus 5.5 and Seed 2.0 Code compared across 19 shared prompts
SpecClaude Opus 5.5Seed 2.0 Code
Input price$4/M tokens$0.5/M tokens
Output price$20/M tokens$3/M tokens
Context window1.0M tokens262K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedSep 2026Aug 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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Seed 2.0 Code377 words
Creative Dish Name: Smoky Hearth Crunch Bowls (Cozy, savory umami crunch made exclusively from 7 pantry staples—no fridge, no fresh produce) 7 Exact Common Pantry Ingredients (No Substitutions Required): 1 (15-oz) can chickpeas (drained, rinsed, patted completely dry) ½ cup quick-cooking rolled oats (old-fashioned…
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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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Seed 2.0 Code1,929 words
Dish Name: Conflux No. 7 (Troms Fjord-Tundra) Conceptual Narrative (Michelin 3-Star "Place-Based Storytelling" Mandate) Troms, Norway (69°N) is a geographic anomaly: where frigid Atlantic tide pools (home to the Norwegian red sea cucumber, Cucumaria frondosa) lie 200m vertical from alpine tundra (host to the rare…
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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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Seed 2.0 Code1,555 words
Explanation for an Experienced Software Engineer (Skeptical of "Next-Word Prediction" as Intelligence) As someone who’s built distributed systems, you’ve almost certainly written code that predicts something—e.g., a log parser that infers a race condition from 5 consecutive partial log lines, or an API rate limiter…
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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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Seed 2.0 Code1,459 words
Core Plausibility Anchor: 1920 Transistor Invention To avoid anachronism, this timeline uses a gradual, realistic transistor evolution: 1920: Bell Labs (Walter Schottky, Oliver Buckley) patents a crude impure germanium point-contact transistor — only useful for low-power audio amplification (radios), not digital logic.
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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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Seed 2.0 Code1,733 words
Analysis of Issues & Remediations We categorize flaws in the original architecture into Race Conditions, Failure Modes, and Scaling Bottlenecks, with specific, actionable solutions and their trade-offs for each. Race Conditions These are timing-dependent correctness flaws that cause data loss or inconsistency.
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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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Seed 2.0 Code721 words
LBO Underwriting: HarborTech Services (HTS) Key Entry & Setup (FY2025 Close = T=0) Metric Calculation Value FY2025 EBITDA Given $120m Purchase EV 12.0x × $120m $1,440m Transaction Fees 2.0% × $1,440m $28.8m Total Uses EV + Fees $1,468.8m Total Debt (5.5x EBITDA) 5.5×$120m $660m - Term Loan (TL): 4.0x EBITDA, 9% cash…
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Our Verdict
Claude Opus 5.5
Claude Opus 5.5
Seed 2.0 Code
Seed 2.0 CodeRunner-up

Not enough votes to call it. On the specs, Claude Opus 5.5 has the edge: newer, bigger context window, major provider backing.

Seed 2.0 Code costs 6.7x 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
Seed 2.0 Code
Input
$0.50
8.0× cheaper
Output
$3.00
6.7× cheaper

Seed 2.0 Code is cheaper on both: 8.0× input, 6.7× 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
Seed 2.0 Code1 host
HostInOutContextUptime
ByteDance Seedfp8$0.50 in·$3.00 out·262k·100% 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 Seed 2.0 Code is developed by ByteDance. Claude Opus 5.5 has a 1.0M token context window vs Seed 2.0 Code's 262K. 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 Seed 2.0 Code 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 Seed 2.0 Code costs $0.5/M input tokens. Seed 2.0 Code is $3.50/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 Seed 2.0 Code 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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