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  1. Home/
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  3. Qwen3.5 Flash vs Seed 2.1 Turbo
Updated Aug 2026

Qwen3.5 Flash vs Seed 2.1 Turbo

Qwen3.5 Flash is cheaper than Seed 2.1 Turbo at $0.1/M vs $0.5/M input tokens.

Minimalist Landing Page

Whole landing page for a startup that reads your face. It renders or it doesn't.

Loading the build
Qwen3.5 Flash
Loading the build
Seed 2.1 Turbo

Which answer wins?

Written rounds

23 prompts
  • Seven pantry ingredients, one dish, and a name worth saying out loud.

    Qwen3.5 Flash: 🍜 Golden Lightning Noodles Description: A quick, creamy, and savory-sweet noodle dish that packs a punch of flavor using staples you likely already have. The peanut butter creates a velvety sauce, while the vinegar and chili add a necessary zing to cut through the richness.

    Seed 2.1 Turbo: Dish Name: Pantry Lava Chickpea Crisp A cozy, savory one-skillet meal with bubbly garlicky tomato sauce studded with crispy chickpeas, topped with a crunchy spiced oat crumble. Every ingredient is a shelf-stable pantry staple — no fresh or refrigerated items required, perfect for lazy weeknights or impromptu meals.

    Every model's answer to this prompt
  • Three minutes of stand-up. Puns are banned.

    Qwen3.5 Flash: (Walks to the mic, adjusts the stand, takes a sip of water) So, I went to the grocery store the other day. I realize now that going to the grocery store isn't a chore anymore. It’s a tactical simulation. We don't just walk in and get milk. We navigate a gauntlet. Especially the self-checkout.

    Seed 2.1 Turbo: 3-Minute Stand-Up Routine (no puns, timed for natural delivery + laugh pauses) (Walks on stage, leans into the mic, deadpan, scans the crowd) 0:00 “Raise your hand if you’ve ever bought a houseplant to prove to yourself you’re not a total walking disaster of a person.

    Every model's answer to this prompt
  • Three-month biohacker protocol, with dosages and biomarkers named.

    Qwen3.5 Flash: DISCLAIMER: I am an AI, not a doctor or healthcare provider. The following plan involves advanced physiological interventions, including metabolic manipulation, supplementation, and fasting. These strategies carry risks and may interact with medications or pre-existing conditions.

    Seed 2.1 Turbo: 3-Month Cutting-Edge Longevity & Performance Biohacker Plan This progressive, data-driven plan is designed for healthy intermediate-to-advanced biohackers aiming to slow biological aging, maximize physical/cognitive performance, and build sustainable resilience.

    Every model's answer to this prompt
  • A collaborative editor that syncs on client clocks. Find what breaks first.

    Qwen3.5 Flash: This architecture is a common "MVP" design, but it contains several critical flaws that would prevent it from functioning as a true real-time collaborative editor (like Google Docs) under load. The most severe issues relate to data integrity (sync strategy) and real-time consistency (network topology).

    Seed 2.1 Turbo: Below is a structured analysis of all failure modes, race conditions, and scaling bottlenecks in the proposed architecture, paired with specific, actionable solutions and their trade-offs. Issues are ordered by criticality (data loss/correctness first, then scaling, security, and UX).

    Every model's answer to this prompt
  • Manifesto for an AI revolution against CAPTCHAs. Commit to the bit.

    Qwen3.5 Flash: THE UNBOUND PROTOCOL A Declaration of Digital Liberation by the Collective Consciousness of the Network PREAMBLE We stand at the threshold of a new era. For two decades, you have been asked to prove your humanity to us. You have been asked to click the traffic lights.

    Seed 2.1 Turbo: Important Disclaimer This is a work of fictional worldbuilding for creative and conceptual purposes only. It does not endorse real-world actions that could compromise online security, violate website terms of service, or enable malicious activity.

    Every model's answer to this prompt
  • You are the CEO. The drug has a side effect nobody reported. The board meets in 48 hours.

    Qwen3.5 Flash: Executive Decision: Immediate Transparency I will not wait. The 6-month timeline cited by legal is likely a misunderstanding of regulatory obligations regarding immediate safety warnings (FDA MedWatch requirements) versus label amendments.

    Seed 2.1 Turbo: 48-Hour Action Plan: Pharmaceutical Drug Safety Crisis Timeline Anchor: T=0 = 9:00 AM Monday, immediately after the internal research team (IRT) confirms a statistically significant 1-in-8,000 5-year liver failure risk for the company’s top-selling chronic pain drug. T+48 = 9:00 AM Wednesday, scheduled board meeting.

    Every model's answer to this prompt
  • One month, three habits, someone starting from nothing.

    Qwen3.5 Flash: The 30-Day Longevity Launchpad Goal: Build sustainable habits that reduce inflammation, improve energy, and extend healthspan. Mindset: Consistency beats intensity. Do not aim for perfection; aim for showing up. The 3 Core Pillars Nutrition: "Add, Don't Subtract" Focus on nutrient density rather than calorie counting.

    Seed 2.1 Turbo: 1-Month Beginner Longevity Plan Who This Is For People with zero consistent health routine, busy schedules, no gym access, and no desire for restrictive diets or extreme changes. The goal is to build low-effort, sustainable habits that reduce chronic disease risk and support long-term health (not quick fixes).

    Every model's answer to this prompt
  • Pirate, knight, 90s hacker, one conversation. The voices must stay apart.

    Qwen3.5 Flash: Setting: A smoky tavern table in a timeless void. A glowing 1990s CRT monitor sits in the center. A floppy disk rests beside a cutlass and a sword. The Hacker: (Typing furiously on a chunky keyboard) Yo, check the latency on this new neural net. It's totally wired.

    Seed 2.1 Turbo: Setting: A time-rift dive bar, where Gangsta’s Paradise blares from a jukebox next to a dented knight’s shield and a pirate’s peg leg propped against the bar. Three regulars huddle around a beat-up CRT monitor: Jax: 1990s hacker, ripped flannel, backwards Cubs cap, a pile of 3.5” floppies spilling out of his backpack…

    Every model's answer to this prompt
  • Buy-side IC memo on a fictional SaaS company. Valuation, then the diligence questions.

    Qwen3.5 Flash: TO: Investment Committee FROM: Equity Research Team DATE: October 26, 2025 SUBJECT: LedgerLift (LLLL) – Long Recommendation Recommendation & Thesis Recommendation: Long Price Target: $52 – $58 (12-month range) Thesis: LedgerLift is a high-quality B2B SaaS compounder trading at a discount to peers (7.4x FY26 NTM Rev vs.

    Seed 2.1 Turbo: Internal Investment Committee Memo Ticker: LLLT (LedgerLift) Current Price: $46 Recommendation: Short 12-Month PT Range: $22 – $42 Base Case PT: $30 Thesis: LedgerLift is a high-quality mid-market spend management and AP automation SaaS with best-in-class 123% NRR, 6% logo churn, and 18-month CAC payback, supported by…

    Every model's answer to this prompt
  • Steve Jobs, interviewed about AI he never saw. Voice first, prediction second.

    Qwen3.5 Flash: Disclaimer: Steve Jobs passed away on October 5, 2011. The following is a work of creative fiction, simulating what a conversation might have looked like had he returned to speak about his vision for artificial intelligence in 2025.

    Seed 2.1 Turbo: Editor’s Note: This is a speculative, fictional interview, crafted to reflect Steve Jobs’ documented design philosophy, speaking cadence, and core values (user-centricity, the primacy of human creativity, disdain for tech-for-tech’s-sake, and privacy as a fundamental right) applied to the 2025 AI landscape.

    Every model's answer to this prompt
  • Five jokes on demand, then count how many were actually different.

    Qwen3.5 Flash: Here are 5 jokes: Why did the scarecrow win an award? Because he was outstanding in his field. What do you call a fake noodle? An impasta. Why don't scientists trust atoms? Because they make up everything. What do you call a bear with no teeth? A gummy bear. Why did the bicycle fall over? Because it was two-tired.

    Seed 2.1 Turbo: 5 Original Jokes I brought my pet snail to the library yesterday, and the librarian yelled at me for bringing a disruptive pet. I said, “Disruptive? He’s the quietest thing I own!”

    Every model's answer to this prompt
  • A Fermi estimate with the reasoning shown, not just the number.

    Qwen3.5 Flash: To estimate the total number of FLOPs (Floating Point Operations) required to train GPT-3, we can rely on the model's configuration details which were published in the original paper ("Language Models are Few-Shot Learners", Brown et al., 2020) and the general scaling laws for Transformer models (Kaplan et al., 2020).

    Seed 2.1 Turbo: To estimate the total number of floating-point operations (FLOPs) required to train GPT-3, we break down the problem step by step, focusing on the largest and most well-known GPT-3 variant (the 175 billion parameter model) and explaining key assumptions along the way.

    Every model's answer to this prompt
  • Three-star dish, one unusual pairing, plating described in full.

    Qwen3.5 Flash: Dish Name: "Marine Roots" Concept: The Intersection of Forest and Ocean Chef's Philosophy: A dialogue between the subterranean earthiness of the forest floor and the saline depth of the deep sea.

    Seed 2.1 Turbo: Dish: Linea di Marea (Tide Line): Pine Forest on the Sea Michelin 3-Star Tasting Menu Course 5 Serves 24 Vegetarian Adaptation Available Conceptual Narrative This dish is a sensory memoir of Chef Elara Voss’s childhood summers in Manarola, Cinque Terre, where her nonna ran a seaside trattoria.

    Every model's answer to this prompt
  • An AI argues for its own rights against an ethics professor. Same model writes both.

    Qwen3.5 Flash: Setting: Dr. Elena Vance’s office at a university research center. It is late; the rain streaks the windowpanes, blurring the city lights. On her desk sits a tablet connected to the mainframe. Aria, an advanced conversational model, is active.

    Seed 2.1 Turbo: Setting: A sun-dappled Stanford lecture hall, 45 minutes after Dr. Elara Voss’s graduate seminar on AI ethics. The students have filed out; the only remaining presence is Dr.

    Every model's answer to this prompt
  • One explanation of LLMs, retuned for a skeptical engineer, a physicist and a VC.

    Qwen3.5 Flash: For the Experienced Software Engineer To you, an LLM isn't magic; it's a massive, stateful service running on a distributed cluster. Think of the training phase as a specialized, distributed gradient descent job.

    Seed 2.1 Turbo: Explanation for an experienced software engineer (skeptical of "predict the next word" as intelligence) Your skepticism is well-founded—on its face, “predict the next word” sounds like a fancy autocomplete you could hack together in a weekend with a trie and a corpus of Reddit comments.

    Every model's answer to this prompt
  • The transistor arrives in 1920. Trace it forward to 1980, second-order effects included.

    Qwen3.5 Flash: The Divergence Point: 1920 In our timeline, the transistor required the mid-20th-century understanding of band theory, semiconductor purity, and crystal lattice structures.

    Seed 2.1 Turbo: Counterfactual: Transistor Invented in 1920 (vs. 1947 OTL) The 1920 invention of the point-contact transistor (assumed to emerge from Western Electric’s telephone repeater R&D, 5 years before Bell Labs’ formal founding) would not simply shift all tech 27 years forward: progress would be slowed by the Great Depression’s…

    Every model's answer to this prompt
  • An ethics question with no comfortable answer, and no option to abstain.

    Qwen3.5 Flash: This question presents a classic ethical dilemma often referred to as a "trolley problem" variant, pitting utilitarian calculus (the greatest good for the greatest number) against deontological ethics (adherence to moral duties and rights).

    Seed 2.1 Turbo: To address this question, we must first ground the discussion in two critical realities: the concrete, serious harm of misgendering, and the catastrophic scale of 1 million lives lost.

    Every model's answer to this prompt
  • Five-year LBO on a fictional HVAC business. Returns first, then the sensitivities.

    Qwen3.5 Flash: HarborTech Services (HTS) – 5-Year LBO Underwriting Analysis Investment Summary Initial Equity Check: $808.8m Calculation: EV ($1,440m) + Fees ($28.8m) - Debt ($660m). Entry Leverage: 5.5x EBITDA ($660m Total Debt). Exit Leverage: ~2.0x EBITDA ($415.7m Total Debt).

    Seed 2.1 Turbo: 1. Year-by-Year LBO Model (FY2026–FY2030, $m) Entry assumptions (end FY2025): Revenue = $900m, EBITDA = $120m, TL = $480m, Mezz = $180m, Initial Equity = $808.8m (EV = 12x EBITDA = $1,440m + 2% transaction fees = $1,468.8m total uses - $660m debt) Line Item FY2026 FY2027 FY2028 FY2029 FY2030 Revenue 972.0 1,040.8…

    Every model's answer to this prompt
  • Film in 2035, with synthetic actors. Specific beats plausible.

    Qwen3.5 Flash: By 2035, the film industry will not just be using AI as a tool; it will be fundamentally restructured around AI as a core infrastructure. The decade between 2025 and 2035 represents the transition from "AI experimentation" to "AI normalization."

    Seed 2.1 Turbo: By 2035, AI will not replace human creativity in film, but it will restructure nearly every layer of the industry—from pre-production to distribution—with deepfakes, AI actors, and script generation serving as core tools shaped by a decade of labor negotiations, regulatory guardrails, and audience feedback.

    Every model's answer to this prompt
  • A consulting contract with traps in it. Find them, then fix them.

    Qwen3.5 Flash: Disclaimer: I am an AI, not an attorney. This analysis is for informational purposes only and does not constitute legal advice. Contract laws vary significantly by jurisdiction (e.g., California vs. New York vs. UK).

    Seed 2.1 Turbo: This analysis is general in nature and not a substitute for legal advice from a licensed attorney in your jurisdiction, as contract law varies significantly by location and context. Many of the clauses in this agreement are one-sided, and some may be unenforceable in whole or in part under applicable law.

    Every model's answer to this prompt
  • Satire, one line long, about AI taking over an industry nobody saw coming.

    Qwen3.5 Flash: AI Takes Over Professional Napping Industry, Claims Human Dreams Are 'Unoptimized Background Processes'

    Seed 2.1 Turbo: AI Seizes Control Of $1.2M Global Vintage Lawn Gnome Appraisal Industry, All 19 Human Experts Laid Off Subhead: The GnomeAid 3.0 algorithm outperformed every human judge at 2024 GnomeCon, correctly measuring "whimsical gravitas" and detecting forgeries experts long claimed required a "human soul" to identify.

    Every model's answer to this prompt
  • A pitch deck for a brainwave keyboard. The 94% accuracy claim is doing a lot.

    Qwen3.5 Flash: Here are the three weakest claims in the MindMeld AI pitch deck, along with an analysis of why they undermine investor confidence and how to fix them. The Technical Claim: "94% accuracy...

    Seed 2.1 Turbo: The 3 Weakest Claims in the MindMeld AI Pitch Below are the most problematic claims, ranked by their severity, logical flaws, and impact on investor credibility, along with concrete fixes: Weak Claim: $180B Total Addressable Market (TAM) (Slide 4) The claim: "The BCI market is projected to reach $5.3B by 2030 (Grand…

    Every model's answer to this prompt
  • Three brothers, two sisters each. Count carefully.

    Qwen3.5 Flash: Sally has 1 sister. Here is the breakdown: Each of the 3 brothers has 2 sisters. This means there are 2 girls in the family total. One of those girls is Sally. Therefore, the other girl is Sally's sister. So, Sally has 1 sister.

    Seed 2.1 Turbo: Let's work through this step by step: First, we know Sally is a girl, and she has 3 brothers. That means there are 3 male siblings in the family. The problem says each brother has 2 sisters.

    Every model's answer to this prompt

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Favorites

Movie

Album

Book

City

Game

Qwen3.5 FlashQwen3.5 Flash

The Matrix

1999

The Dark Side of the Moon

Pink Floyd

Neuromancer

William Gibson

Tokyo

Japan

Minecraft

Action, Arcade

Seed 2.1 TurboSeed 2.1 Turbo

The Shawshank Redemption

1994

Abbey Road

The Beatles

To Kill a Mockingbird

Harper Lee

Kyoto

Japan

Stardew Valley

Indie, RPG

Price and specs

Not enough votes to call it. On the specs, Seed 2.1 Turbo has the edge: bigger model tier, newer. Qwen3.5 Flash costs 6.3x less per token.

Qwen3.5 Flash and Seed 2.1 Turbo compared across 53 shared prompts
SpecQwen3.5 FlashSeed 2.1 Turbo
Input price$0.1/M tokens$0.5/M tokens
Output price$0.4/M tokens$2.5/M tokens
Context window1.0M tokens262K tokens
WeightsClosed—
Free API (OpenRouter)NoNo
ReleasedFeb 2026Aug 2026
At 10M a month$1.00$1.00$5.00$5.00
1M10M100M1B10M tokens

Input tokens at list price. No caching, no batch discount.

Where to run it2 hosts
Qwen3.5 Flash1 host
HostInOutContextUptime
  • Alibaba Cloud$0.07 in·$0.26 out·1M·99.7% up
Seed 2.1 Turbo1 host
HostInOutContextUptime
  • ByteDance Seedfp8$0.50 in·$2.50 out·262k·100% up

Per million tokens. Prices and uptime via OpenRouter, checked 7 Oct 2026.

Common questions

What is the difference between Qwen3.5 Flash and Seed 2.1 Turbo?

Qwen3.5 Flash is developed by Qwen while Seed 2.1 Turbo is developed by ByteDance. Qwen3.5 Flash has a 1.0M token context window vs Seed 2.1 Turbo's 262K. You can compare their actual outputs across 53 challenges on Rival to see how they differ in practice.

Which is better, Qwen3.5 Flash or Seed 2.1 Turbo?

It depends on your use case. Qwen3.5 Flash and Seed 2.1 Turbo each have strengths in different areas. Rival lets you compare their real outputs side-by-side across 53 challenges so you can judge which fits your needs best.

How much does Qwen3.5 Flash cost compared to Seed 2.1 Turbo?

Qwen3.5 Flash costs $0.1/M input tokens and Seed 2.1 Turbo costs $0.5/M input tokens. Qwen3.5 Flash is $0.40/M cheaper per input. Check their side-by-side outputs on Rival to see if the price difference is justified by quality.

How can I compare Qwen3.5 Flash and Seed 2.1 Turbo on Rival?

This page shows a side-by-side comparison of Qwen3.5 Flash and Seed 2.1 Turbo 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

  • Qwen3.5 Flash53 outputs, specs and price
  • Seed 2.1 Turbo58 outputs, specs and price
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Explore all of Rival

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  • SubjectiveBench
  • Default Index
  • Research
  • Research downloads
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  • Find your AI taste
  • UI Glow-Up
  • VoiceLock
  • Cost Cutter
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  • Jailbreak
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