ResearchLLM Verifications Leaderboard

Data as of · 78 models, 80 questions · reviewed by Suhas Bhairav · methodology

Head to head · tested 27 Oct 2026

Claude Opus 5.5 vs Muse Spark Open: accuracy, speed and price

Similar accuracy; Muse Spark Open costs less per question.

AnthropicClaude Opus 5.585.0% score · #1$0.015 per question129 tok/sMetaMuse Spark Open77.5% score · #9$0.0045 per question220 tok/s

Verdict

Built from the measurements below

  • Accuracy is too close to call: Claude Opus 5.5 scored 85.0% and Muse Spark Open 77.5% on the same 80 questions, a gap within what chance alone could produce.
  • Muse Spark Open is 3.2× cheaper per question as billed ($0.0045 vs $0.015), reasoning tokens included.
  • Muse Spark Open generates text 1.7× faster: 220 tokens per second against 129.
  • Muse Spark Open starts answering sooner: 0.5 s to the first token, against 2.3 s for Claude Opus 5.5.

Which should you choose?

Choose Muse Spark Open for the lower cost per correct answer ($0.0058 against $0.017), faster streaming, a quicker first token and open weights you can run yourself.

Accuracy gap +7.5 points (z = 1.22). A winner is called only when z is at least 1.96, the usual 95% threshold. Speed, latency and price need a 10% margin.

Head to head

Same questions, same prompt, same API

MeasureClaude Opus 5.5Muse Spark OpenEdge
Verification scoreHigher is better85.0%77.5%Too close to call
Cost per questionLower is better$0.015$0.0045Muse Spark Open
Output speedHigher is better129220Muse Spark Open
Time to first tokenLower is better2.3 s0.5 sMuse Spark Open
End-to-end response timeLower is better7.6 s3.2 sMuse Spark Open
Tokens per questionLower is better645964Claude Opus 5.5
Context windowHigher is better1M1MSimilar

Side by side

Bars are scaled to the larger of the two values. The winner on each measure is marked in bold.

Every measure

Claude Opus 5.5 first, Muse Spark Open second

Verification scorehigher is better
Claude Opus 5.585.0%
Muse Spark Open77.5%
Cost per questionlower is better
Claude Opus 5.5$0.015
Muse Spark Open$0.0045
Output speedhigher is better
Claude Opus 5.5129
Muse Spark Open220
Time to first tokenlower is better
Claude Opus 5.52.3 s
Muse Spark Open0.5 s
End-to-end response timelower is better
Claude Opus 5.57.6 s
Muse Spark Open3.2 s
Tokens per questionlower is better
Claude Opus 5.5645
Muse Spark Open964
Context windowhigher is better
Claude Opus 5.51M
Muse Spark Open1M

Score vs. cost per question

Both models in color, every other model in grey

Most attractive quadrant0255075100$0.00001$0.0001$0.001$0.01$0.10Cost per question (USD, log) →Verification score (%) →Qwen3.8 2.4T A95BCommand AReka Flash 3Gemma 4 26B A4BGemma 4 31BQwen3.5 397B A17BHermes 4 405BMuse WonderGrok 4.7o3gpt-oss-20bMinistral 3 3B 2512Nova Micro 1.0Phi 4Granite 4.2 8BHy3GLM 5.3 FlashSolar Pro 4Trinity Large ThinkingMiniMax M3Mistral Large 4Claude Opus 5.5GPT-6.1 SolGemini 4 ArgonGPT-5.4GPT-6 Lunagpt-oss-120bLlama 4 Maverick

Specifications and pricing

From OpenRouter's catalogue, plus the leaderboard's test dates

SpecificationClaude Opus 5.5Muse Spark Open
CreatorAnthropicMeta
Released22 Sept 202615 Oct 2026
Weights—Open weights
ReasoningYesYes
Inputtext, image, filetext, image, video, file, audio
Outputtexttext
Context window1M tokens1M tokens
Knowledge cutoff——
List price in / out per 1M$4 / $20$1.25 / $4.25
Blended price per 1M (3:1)$8.00$2.00
Cheapest hostAmazon Bedrock · $4 / $20Makora · $1.25 / $4.25
Hosts on OpenRouter56
Last tested25 Oct 202626 Oct 2026

Compare any two models →

Claude Opus 5.5 vs Muse Spark Open: frequently asked questions

Is Claude Opus 5.5 better than Muse Spark Open?
On accuracy they are statistically tied: Claude Opus 5.5 scored 85.0% and Muse Spark Open 77.5% on the same 80 questions from open datasets. Similar accuracy; Muse Spark Open costs less per question.
Which is cheaper, Claude Opus 5.5 or Muse Spark Open?
Muse Spark Open is cheaper: $0.0045 per question as billed, against $0.015. List prices: Claude Opus 5.5 $4 in / $20 out, Muse Spark Open $1.25 in / $4.25 out per million tokens.
Which is faster, Claude Opus 5.5 or Muse Spark Open?
Muse Spark Open is faster at 220 output tokens per second, against 129. Time to first token: 2.3 s for Claude Opus 5.5, 0.5 s for Muse Spark Open.
Which has the larger context window, Claude Opus 5.5 or Muse Spark Open?
Both accept about the same amount of context: 1M and 1M tokens.