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Comparison · 2 models · Updated Nov 2, 2026

Muse Spark Open vs Claude Opus 5.5

Too close to call on our weighted score (Claude Opus 5.5 69, Muse Spark Open 68). The right pick depends on what you value most.

  1. Meta

    Muse Spark Open

    Released Oct 15, 2026

    68/100
    • ECI155.1
    • Price$1.25 / $4.25
    • Context1.05M
    Full specs Remove Muse Spark Open

  2. Anthropic

    Claude Opus 5.5

    Released Sep 22, 2026

    69/100
    • ECI168.4
    • Price$4.00 / $20.00
    • Context1M
    Full specs Remove Claude Opus 5.5

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01 — Verdict

Too close to call

It is close. Our weighted score puts them within 1 points (Claude Opus 5.5 69/100, Muse Spark Open 68/100), so choose by what matters most for your work: Claude Opus 5.5 for raw capability, Muse Spark Open on price and Muse Spark Open for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

  • CapabilityClaude Opus 5.5Capabilities Index (ECI): Claude Opus 5.5 168.4 · Muse Spark Open 155.1
  • Lowest priceMuse Spark OpenMuse Spark Open $2.00 · Claude Opus 5.5 $8.00 per 1M tokens (3:1 blend)
  • Longest contextMuse Spark OpenMuse Spark Open 1,048,576 · Claude Opus 5.5 1,000,000 tokens
  • Widest inputsMuse Spark OpenMuse Spark Open: Text, Images, Audio, Video · Claude Opus 5.5: Text, Images, PDFs
  • Self-hostingMuse Spark OpenPublishes downloadable weights (Muse Model License)
How the score is built
MeasureWeightMuse Spark OpenClaude Opus 5.5
CapabilityCapabilities Index (ECI)50%8399
Price25%347
Inputs & features15%8080
Context window10%6160
Overall100%68/10069/100
02 — Side by side

Every spec in one table

Highlighted cells lead their row. Dashes mean the data is not published.

Muse Spark Open vs Claude Opus 5.5 specifications side by side
SpecificationMuse Spark OpenMetaClaude Opus 5.5Anthropic
Capability
Capabilities Index (ECI)155.1168.4 (best)
ECI rank#39 of 165#2 of 165 (best)
GPQA DiamondGraduate-level science questions88.6%90.6% (best)
FrontierMath Tiers 1–3Research-level mathematics69.8%91.2% (best)
OTIS Mock AIME 2024–2025Competition mathematics98.1%100% (best)
SimpleQA VerifiedShort factual questions56.6%72.2% (best)
Price per million tokens
Input$1.25 (best)$4.00
Output$4.25 (best)$20.00
Cached input—$0.20
Blended (3:1)$2.00 (best)$8.00
Long-context rateSame rateSame rate
Price sourceMedian of 16 providersOfficial Anthropic API
Limits
Context window1,048,576 tokens (best)1,000,000 tokens
Max output131,072 tokens (best)128,000 tokens
Inputs and features
TextYesYes
ImagesYesYes
PDFsNoYes
AudioYesNo
VideoYesNo
ReasoningYesYeslow · medium · high · xhigh · max
Tool callingYesYes
Structured outputNoYes
Availability
WeightsOpenMuse Model LicenseProprietary
API model ID—claude-opus-5-5
API providers1636 (best)
ReleasedOct 15, 2026Sep 22, 2026
Knowledge cutoffJan 4, 2026Jun 2026
03 — Cost

What would a month cost?

Enter your expected volume in millions of tokens. List prices only; caching and batch discounts would lower these.

  • Muse Spark Open$21.00
  • Claude Opus 5.5$80.00
04 — Questions

Which should you choose?

Which is better: Muse Spark Open or Claude Opus 5.5?

It is close. Our weighted score puts them within 1 points (Claude Opus 5.5 69/100, Muse Spark Open 68/100), so choose by what matters most for your work: Claude Opus 5.5 for raw capability, Muse Spark Open on price and Muse Spark Open for long inputs. The score weighs capability 50%, price 25%, inputs & features 15%, context window 10%.

Which is cheaper, Muse Spark Open or Claude Opus 5.5?

Muse Spark Open is cheaper at $1.25 input / $4.25 output per million tokens (median across 16 API providers). Claude Opus 5.5 costs $4.00 input / $20.00 output per million tokens (official Anthropic API price). At a typical mix of three input tokens to one output token, that is $2.00 per million tokens for Muse Spark Open versus $8.00 for Claude Opus 5.5 (4× as much).

Which scores higher on benchmarks?

Claude Opus 5.5 scores higher on the Capabilities Index (ECI): Claude Opus 5.5 168.4 (#2 of 165) and Muse Spark Open 155.1 (#39 of 165). Their confidence ranges do not overlap (165.4–173.0 vs 153.1–157.3), so the gap is a real one. On individual benchmarks: GPQA Diamond — Claude Opus 5.5 90.6%, Muse Spark Open 88.6%; FrontierMath Tiers 1–3 — Claude Opus 5.5 91.2%, Muse Spark Open 69.8%; OTIS Mock AIME 2024–2025 — Claude Opus 5.5 100%, Muse Spark Open 98.1%; SimpleQA Verified — Claude Opus 5.5 72.2%, Muse Spark Open 56.6%.

Which is better for coding?

There are no published SWE-bench Verified results for Muse Spark Open and Claude Opus 5.5 yet, so there is no like-for-like coding score. On overall capability, Claude Opus 5.5 leads, which tends to carry over to coding, but test on your own codebase. Both support tool calling for agent workflows.

Which has the bigger context window?

Muse Spark Open has the largest context window at 1,048,576 tokens, against 1,000,000 for Claude Opus 5.5. Maximum output per response: Muse Spark Open up to 131,072, Claude Opus 5.5 up to 128,000 tokens.

Which can read images, PDFs, audio or video?

Muse Spark Open accepts text, images, audio and video; Claude Opus 5.5 accepts text, images and PDFs. Muse Spark Open handles the widest range of inputs.

Are any of these open source?

Muse Spark Open publishes its weights (Muse Model License) and can be self-hosted; Claude Opus 5.5 is proprietary.

Which is newer?

Muse Spark Open is the newest, released Oct 15, 2026. Claude Opus 5.5 came out Sep 22, 2026. Knowledge cutoff: Muse Spark Open Jan 4, 2026, Claude Opus 5.5 Jun 2026.

How do you decide the winner?

Each model gets a 0–100 score on capability (50%, independent benchmark results); price (25%, blended price per million tokens (3 input : 1 output), log scale); inputs & features (15%, image, PDF, audio and video input, tool calling, structured output and reasoning); context window (10%, maximum tokens per request, log scale). Dimensions missing for any model are dropped and the remaining weights rescaled, so every model is judged on the same evidence. Specs and prices come from public model listings and the labs’ own API pages; capability scores come from independent benchmark runs. Data updated Nov 2, 2026.

05 — Keep comparing

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