Claude Opus 5.5 vs Muse Spark Open
Updated October 21, 2026. 25 benchmarks have a result for both. Coding is ranked on the Vibe Coding Index; every other board is shown as published.
vs boards won of 25 shared
Decision reading
Pick Claude Opus 5.5 for coding: it scores 92.2 on the Vibe Coding Index against 62.1 for Muse Spark Open.
Pick Muse Spark Open when output tokens cost 4.7x less, or when the context window is larger, 1.05M against 1M tokens.
Model AClaude Opus 5.5Anthropic92.2/1002 independent benchmarksNo cost per solved taskModel BMuse Spark OpenMeta62.1/1002 independent benchmarksNo cost per solved task
- Shared results
- 25
- Claude Opus 5.5 only
- 82
- Muse Spark Open only
- 1
- Like-for-like categories
- 6 of 9
Shared results can support a head-to-head reading. Results only one model has describe coverage, not superiority.
Which one for your work
Each card is decided by one number both models carry. Where only one has it, the card says so and makes no call.
Coding
Vibe Coding Index, four public coding benchmarks
Claude Opus 5.5
Claude Opus 5.5 scores 92.2 against 62.1.
2 benchmarks behind each score
Intelligence
AA Intelligence Index
No call
Only Claude Opus 5.5 has a AA Intelligence Index result, 57.6.
Directional only
Web design
Design Arena: websites
Claude Opus 5.5
Claude Opus 5.5 leads, 1335 against 1311.
Same board, both measured
General
Vals Index
No call
Only Claude Opus 5.5 has a Vals Index result, 70.2%.
Directional only
Long documents
Listed context window
Muse Spark Open
Muse Spark Open takes 1.05M tokens against 1M.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Muse Spark Open
Claude Opus 5.5 $0.014, Muse Spark Open $0.0034 per turn.
List prices
At a glance
- Coding index
- Claude Opus 5.5 92.2 from 2 benchmarks, Muse Spark Open 62.1 from 2 benchmarks.
- Widest category
- Agentic work, 26.4 points apart on average over 8 shared benchmarks.
- Widest single gap
- LiveBench long agentic: Claude Opus 5.5 85.0% against Muse Spark Open 18.9%, 66.1 points apart on a 0 to 100 scale.
- Output price
- Claude Opus 5.5 $20.00 against Muse Spark Open $4.25 per million output tokens, 4.7x apart.
- Context window
- Claude Opus 5.5 takes 1M tokens, Muse Spark Open 1.05M.
Benchmark by benchmark
First the score: boards each model leads, per category, where both have a result. Then every board, a category to a fold; bars are each result on a 0 to 100 scale, so compare the two in a row, not one row with another.
| Category | Claude Opus 5.5 | Bars | Muse Spark Open | Ties |
|---|---|---|---|---|
| Coding | 9 | 0 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 7 | 1 | ||
| Reasoning | 2 | 0 | ||
| Web design | 3 | 0 | ||
| General | 2 | 0 | ||
| All shared boards | 24 | 1 |
CodingLike-for-likeFour of these boards feed the Vibe Coding Index90
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| LiveBench coding | 96.3% | 73.6% | Claude Opus 5.5 |
| LMArena WebDev | 1807 | 1528 | Claude Opus 5.5 |
| Terminal-Bench 4 (Vals AI) | 65.2% | 6.6% | Claude Opus 5.5 |
| Vibe Code Bench (Vals AI) | 90.3% | 76.2% | Claude Opus 5.5 |
| Code migration (Vals AI) | 66.7% | 21.2% | Claude Opus 5.5 |
| ProgramBench (Vals AI) | 18.5% | Not measured | Only Claude Opus 5.5 measured |
| IOI (Vals AI) | 95.1% | Not measured | Only Claude Opus 5.5 measured |
| Terminal-Bench 2.1 (Vals AI) | 87.6% | Not measured | Only Claude Opus 5.5 measured |
| SWE-bench Multimodal (Vals AI) | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| Vibe Code Bench 1-100 (Vals AI) | 30.4% | Not measured | Only Claude Opus 5.5 measured |
| CyberBench (Vals AI) | 74.6% | Not measured | Only Claude Opus 5.5 measured |
| SciCode | 66.9% | 58.4% | Claude Opus 5.5 |
| FrontierCode | 54.6% | Not measured | Only Claude Opus 5.5 measured |
| FrontierSWE | 62.3% | Not measured | Only Claude Opus 5.5 measured |
| MirrorCode | 77.4% | Not measured | Only Claude Opus 5.5 measured |
| ALE-Bench | 2147.4 | 1590.1 | Claude Opus 5.5 |
| LMArena Text: coding | 1545 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: software and IT | 1538 | Not measured | Only Claude Opus 5.5 measured |
| LMArena WebDev: React | 1855 | 1529 | Claude Opus 5.5 |
| LMArena WebDev: HTML | 1753 | 1495 | Claude Opus 5.5 |
| LMArena WebDev: from an image | 1753 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 17 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| AA Intelligence Index | 57.6 | Not measured | Only Claude Opus 5.5 measured |
| Epoch Capabilities Index | 168.8 | 155.1 | Claude Opus 5.5 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index71
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| Design Arena: agents building web apps | 1316 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: agents building mobile apps | 1311 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: spreadsheets | 1359 | Not measured | Only Claude Opus 5.5 measured |
| LiveBench research | 85.0% | 80.3% | Claude Opus 5.5 |
| LiveBench browser | 80.0% | 36.0% | Claude Opus 5.5 |
| LiveBench long agentic | 85.0% | 18.9% | Claude Opus 5.5 |
| SREBench (Vals AI) | 33.6% | Not measured | Only Claude Opus 5.5 measured |
| Finance Agent (Vals AI) | 58.6% | 61.3% | Muse Spark Open |
| Tax Agent Bench (Vals AI) | 45.6% | 26.3% | Claude Opus 5.5 |
| Legal Research Bench (Vals AI) | 50.5% | 38.5% | Claude Opus 5.5 |
| Harvey's Legal Agent Benchmark (Vals AI) | 9.2% | Not measured | Only Claude Opus 5.5 measured |
| Excel Modeling Benchmark (Vals AI) | 75.9% | 53.7% | Claude Opus 5.5 |
| BioMysteryBench (Vals AI) | 79.3% | Not measured | Only Claude Opus 5.5 measured |
| Terminal-Bench-Science (Vals AI) | 47.1% | Not measured | Only Claude Opus 5.5 measured |
| Vals Science Index | 58.7% | Not measured | Only Claude Opus 5.5 measured |
| Time Horizon Index (Vals AI) | 91.3% | Not measured | Only Claude Opus 5.5 measured |
| CUA-bench (Vals AI) | 14.0% | Not measured | Only Claude Opus 5.5 measured |
| Robo-bench (Vals AI) | 14.6% | Not measured | Only Claude Opus 5.5 measured |
| APEX-Agents | 73.5% | 33.4% | Claude Opus 5.5 |
| Remote Labor Index | 21.3% | Not measured | Only Claude Opus 5.5 measured |
| SpireClimb | 3.3% | Not measured | Only Claude Opus 5.5 measured |
| Vending-Bench 2 | $9,235 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Search | 1213 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 16 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| LiveBench reasoning | 92.2% | 73.7% | Claude Opus 5.5 |
| MysteryMechanism (Vals AI) | 49.5% | Not measured | Only Claude Opus 5.5 measured |
| GPQA Diamond (Artificial Analysis run) | Not measured | 89.0% | Only Muse Spark Open measured |
| Humanity's Last Exam (Artificial Analysis run) | 61.4% | 43.9% | Claude Opus 5.5 |
| GPQA Diamond (Epoch AI run) | 90.6% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI | 98.5% | Not measured | Only Claude Opus 5.5 measured |
| ARC-AGI-2 | 93.3% | Not measured | Only Claude Opus 5.5 measured |
| Chess puzzles | 67.0% | Not measured | Only Claude Opus 5.5 measured |
| Mystery game puzzles | 71.0% | Not measured | Only Claude Opus 5.5 measured |
| EBR-bench | 71.4% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: hard prompts | 1536 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: expert | 1549 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: hard prompts in English | 1535 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: diagrams | 1345 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: homework | 1362 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 6 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| OTIS Mock AIME | 100.0% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tiers 1 to 3 | 91.2% | Not measured | Only Claude Opus 5.5 measured |
| FrontierMath, tier 4 | 95.0% | Not measured | Only Claude Opus 5.5 measured |
| ProofBench | 100.0% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: math | 1518 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: mathematical work | 1516 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 7 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| MedCode (Vals AI) | 49.8% | Not measured | Only Claude Opus 5.5 measured |
| SimpleQA Verified | 72.2% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: science | 1524 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: medicine and healthcare | 1509 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: legal and government | 1518 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: business and finance | 1494 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 11 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| Design Arena: websites | 1335 | 1311 | Claude Opus 5.5 |
| Design Arena: UI components | 1390 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: game dev | 1457 | 1290 | Claude Opus 5.5 |
| Design Arena: data viz | 1397 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: 3D | 1477 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: all code categories | 1390 | Not measured | Only Claude Opus 5.5 measured |
| Design Arena: SVG | 1332 | Not measured | Only Claude Opus 5.5 measured |
| LiveBench design | 86.9% | 60.3% | Claude Opus 5.5 |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index20
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| Vals Index | 70.2% | Not measured | Only Claude Opus 5.5 measured |
| LiveBench data analysis | 80.3% | 60.2% | Claude Opus 5.5 |
| Public Benefits Bench (Vals AI) | 70.6% | Not measured | Only Claude Opus 5.5 measured |
| SAGE (Vals AI) | 45.8% | Not measured | Only Claude Opus 5.5 measured |
| MedScribe (Vals AI) | 91.4% | Not measured | Only Claude Opus 5.5 measured |
| Long context reasoning (AA-LCR) | 84.7% | 78.3% | Claude Opus 5.5 |
| DTBench | 98.9% | Not measured | Only Claude Opus 5.5 measured |
| LMCA | 68.2% | Not measured | Only Claude Opus 5.5 measured |
| Furniture assembly | 83.3% | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text | 1516 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: instruction following | 1537 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: creative writing | 1535 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision | 1321 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: English | 1519 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: non-English | 1507 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Chinese | 1582 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Japanese | 1534 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: French | 1493 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Spanish | 1508 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: Russian | 1517 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: multi-turn | 1501 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: longer queries | 1532 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: writing and language | 1532 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Text: entertainment and media | 1515 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: English | 1317 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: reading text | 1326 | Not measured | Only Claude Opus 5.5 measured |
| LMArena Vision: creative writing | 1320 | Not measured | Only Claude Opus 5.5 measured |
| Neither model has a result on the other 19 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Claude Opus 5.5 | Muse Spark Open | Leader |
|---|---|---|---|
| Neither model has a result on 5 boards here | |||
What each workload costs
Three fixed token mixes at each model's listed price, so per-token rates become a bill.
Chat turn
1K input + 500 output tokens
Claude Opus 5.5$0.014Fits in one request
Muse Spark Open$0.0034Fits in one request
Muse Spark Open costs less
Repository review
50K input + 3K output tokens
Claude Opus 5.5$0.260Fits in one request
Muse Spark Open$0.075Fits in one request
Muse Spark Open costs less
Agent loop
200K input + 10K output tokens
Claude Opus 5.5$1.00Fits in one request
Muse Spark Open$0.292Fits in one request
Muse Spark Open costs less
Listed OpenRouter rates, without cache or batch discounts. A workload that does not fit a model's context window would need splitting.
Specification differences
The leading value in a row is marked; a row with a missing value names no leader. Our two rows are marked in red.
| Specification | Anthropic Claude Opus 5.5 | Meta Muse Spark Open |
|---|---|---|
| Maker | Anthropic | Meta |
| Weights | No public weights listed | Open weights |
| Released | September 22, 2026 | October 15, 2026 |
| Context window | 1M | 1.05M |
| Input $/Mtok | $4.00 | $1.25 |
| Output $/Mtok | $20.00 | $4.25 |
| Coding index | 92.2 | 62.1 |
| Independent measurements behind it | 2 | 2 |
| Cost per solved task | Not computable | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Claude Opus 5.5 better than Muse Spark Open for coding?
Pick Claude Opus 5.5 for coding: it scores 92.2 on the Vibe Coding Index against 62.1 for Muse Spark Open. Pick Muse Spark Open when output tokens cost 4.7x less, or when the context window is larger, 1.05M against 1M tokens.
Which is cheaper, Claude Opus 5.5 or Muse Spark Open?
Claude Opus 5.5 costs $4.00 per million input tokens and $20.00 per million output tokens; Muse Spark Open costs $1.25 and $4.25. Cost per solved task is known for neither of them.
Which has the bigger context window, Claude Opus 5.5 or Muse Spark Open?
Muse Spark Open, with 1.05M tokens against 1M.
How many benchmarks is the Claude Opus 5.5 vs Muse Spark Open comparison based on?
25 benchmarks have a result for both models as of October 21, 2026. Claude Opus 5.5's coding index rests on 2 independent benchmarks and Muse Spark Open's on 2. Where only one model has a result, the page says so instead of naming a winner.