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  5. Claude Opus 5.5vsMistral Devstral Small 1.1
Updated Sep 2026

Claude Opus 5.5vsMistral Devstral Small 1.1

Mistral Devstral Small 1.1 is cheaper than Claude Opus 5.5 at $0.1/M vs $4/M input tokens.

Claude Opus 5.5 and Mistral Devstral Small 1.1 compared across 19 shared prompts
SpecClaude Opus 5.5Mistral Devstral Small 1.1
Input price$4/M tokens$0.1/M tokens
Output price$20/M tokens$0.3/M tokens
Context window1.0M tokens—
WeightsClosedOpen
Free API (OpenRouter)NoNo
ReleasedSep 2026Jul 2025
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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Mistral Devstral Small 1.1254 words
Dish Name: "Pantry Pasta Primavera" Ingredients: Pasta (any shape, 8 oz or 225g) Canned tomatoes (14 oz or 400g) Onion (1 medium) Garlic (2 cloves) Olive oil (2 tbsp) Salt (1 tsp) Black pepper (½ tsp) Instructions: Boil the pasta: Cook the pasta according to package instructions until al dente.
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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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Mistral Devstral Small 1.1645 words
Potential Failure Modes, Race Conditions, and Scaling Bottlenecks WebSocket Connection Failures: Failure Mode: WebSocket connections can drop due to network issues or server crashes. Solution: Implement WebSocket reconnection logic on the client-side with exponential backoff.
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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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Mistral Devstral Small 1.1387 words
Year-by-Year Table (FY2026–FY2030) Year Revenue EBITDA Cash Interest (Term Loan) Cash Interest (Mezz) PIK (Mezz) Cash Taxes Capex ΔNWC Free Cash Flow After Debt Service Ending Term Loan Balance Ending Mezzanine Balance 2026 $972m $136.08m $36.00m $13.50m $2.70m $18.42m $29.16m $4.86m $11.14m $344.00m $108.00m 2027…
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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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Mistral Devstral Small 1.1662 words
3-Month Longevity Plan for a Biohacker Month 1: Foundation and Assessment Week 1-2: Initial Assessment and Baseline Establishment Wearable Tracking: Devices: Oura Ring, Whoop Strap, and Apple Watch. Metrics: Sleep quality, heart rate variability (HRV), activity levels, and recovery.
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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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Mistral Devstral Small 1.1633 words
Here are the clauses that could be exploited against the contractor, along with suggested modifications and legal reasoning: Scope (Clause 1) Exploitable: Client can modify the scope at any time without additional compensation.
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Ethical Dilemma with Stakeholders

You're the CEO of a pharmaceutical company. Your best-selling drug ($2B annual revenue, used by 4 million patients for chronic pain) has…

Claude Opus 5.51,853 words
The Next 48 Hours: CEO Action Plan The Core Decision We disclose. The question is how to do it well, not whether. Before the schedule, here are the three facts that drive every decision below. 1. The harm is concrete.
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Mistral Devstral Small 1.1891 words
Here's a specific, hour-by-hour action plan for the next 48 hours, considering all the factors you've mentioned: Day 1: Hour 1-2: Gather all relevant information Meet with your internal research team to get a comprehensive understanding of the side effect, its severity, and the data supporting it.
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Our Verdict
Claude Opus 5.5
Claude Opus 5.5
Mistral Devstral Small 1.1
Mistral Devstral Small 1.1Runner-up

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

Mistral Devstral Small 1.1 costs 67x less per token.

Slight edge

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
Mistral Devstral Small 1.1
Input
$0.10
40× cheaper
Output
$0.30
67× cheaper

Mistral Devstral Small 1.1 is cheaper on both: 40× input, 67× output.

Where to run it

4 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
Mistral Devstral Small 1.1

No hosts listed on OpenRouter.

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 Mistral Devstral Small 1.1 is developed by Mistral AI. 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 Mistral Devstral Small 1.1 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 Mistral Devstral Small 1.1 costs $0.1/M input tokens. Mistral Devstral Small 1.1 is $3.90/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 Mistral Devstral Small 1.1 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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