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Muse Spark Open vs Claude Opus 5.5
Claude Opus 5.5 scores higher than Muse Spark Open on all 5 public leaderboards that rate both. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Muse Spark Open is at 16.7 and Claude Opus 5.5 at 90.9 (out of 100).
Scores as published by each board; table composed November 13, 2026.
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Leaderboard by leaderboard
| Board | Muse Spark Open | Claude Opus 5.5 | Higher |
|---|---|---|---|
| LMArena Elo (community votes) | 1,526.3 | 1,814.7 | Claude Opus 5.5 |
| LiveBench global average (0-100) | 48.5 | 83.4 | Claude Opus 5.5 |
| Vals AI Vals Index accuracy % · weighted finance + coding tasks | 48.6 | 70.1 | Claude Opus 5.5 |
| Artificial Analysis intelligence index · measured runs only | 24.9 | 59.1 | Claude Opus 5.5 |
| Epoch AI Epoch Capabilities Index (ECI) · many benchmarks on one scale | 155.4 | 168.5 | Claude Opus 5.5 |
Raw scores are each board's own scale, so compare within a row, not across rows. Full table: the bench index.
For coding
On the ArtificialWatch coding index, Muse Spark Open is at 21.6 (#43 of 48) and Claude Opus 5.5 at 90 (#3). Claude Opus 5.5 scores higher on both coding boards that rate them.
| Coding board | Muse Spark Open | Claude Opus 5.5 |
|---|---|---|
| LiveBench · Coding | 55.1 | 87.1 |
| Vals Vibe Code Bench | 76.2 | 90.3 |
Muse Spark Open at a glance
- Developer
- Meta
- Status
- Live since October 15, 2026
Live — Oct 15 · Meta's open-weights Spark: 816B total / 42B active mixture-of-experts with a 1.8B perception encoder, 1M context, text, image, video and audio in, text out · reasoning effort low / medium / high / xhigh, default xhigh · weights on Hugging Face in BF16 and NVFP4, gated, under Meta's Muse Model License · Meta says NVFP4 needs at least 700GB of VRAM and BF16 2TB, and that it is tuned to run on two M5 Ultra Mac Studios with MLX · OpenRouter: $1.25 / $4.25 per 1M through BaseTen (FP4), the same price as Muse Spark 1.3 · Meta's own table, against open-weight models: Artificial Analysis Intelligence Index 39, behind GLM 5.3 (45), Kimi K3 (44) and Qwen3.8 (40); ahead of all of them on JobBench (61.8) and MCP-Atlas (89.2); behind on Terminal-Bench 2.1 (76.4 vs Kimi K3's 85.0) · Artificial Analysis has no page of its own for it yet (Oct 15).
Meta releases Muse Spark Open: 816B open weights at $1.25 / $4.25, and its own table puts it behind Kimi K3 and GLM 5.3
2026-10-15 · Meta has released Muse Spark Open, an open-weights version of its Spark model: 816 billion parameters in total, 42 billion active per token, with a 1M-token context. Meta's model card on Hugging Face dates the release October 15.
Claude Opus 5.5 at a glance
- Developer
- Anthropic
- Status
- Live since September 22, 2026
- API price
- $4 input / $20 output per 1M tokens · Anthropic, claude-opus-5-5
- Context window
- 1M tokens
Live — Sep 22 · $4/$20 per MTok, down from Opus 5 at $5/$25 · 1M ctx / 128K out · adaptive thinking always on, default effort medium · cache reads 5% of base input · Anthropic now says start here for most workloads, and Opus 5 is legacy · fast mode (speed: 'fast', up to 2.5x the output tokens per second by Anthropic's figure) at $8 / $40 per MTok, double standard, left research preview Oct 15 with no waitlist, access request or beta header; on the Claude API and on Claude in Microsoft Foundry (Azure-hosted), not on Bedrock, Google Cloud, Claude Platform on AWS, the Batch API or Priority Tier; @ClaudeDevs says Google Cloud is coming soon (Anthropic's fast mode docs, read Oct 16).
AI models go live a median of 4 months after their knowledge ends: Claude Opus 5.5 knows up to June 2026, Gemini 4 Argon only to March
2026-11-06 · Of the 22 live AI models whose labs publish a knowledge cutoff, the median went live 4 months after its training data ends, by ArtificialWatch's count. The latest published cutoff we found is June 2026, for Anthropic's four current Claude models and OpenAI's GPT-6.1 Terra.
SemiAnalysis launches GDPx: Opus 5.5 leads at 12%, Gemini 4 Carbon close behind
2026-11-02 · SemiAnalysis released GDPx on November 2, a new agentic benchmark of 206 tasks across 11 domains, and the best model it tested scores 12%. Claude Opus 5.5 leads at 12.0, Gemini 4 Carbon is second at 10.9 and GPT-6 Astra third at 9.6. We read the leaderboard directly at gdpx.semianalysis.com.
Muse Spark Open vs Claude Opus 5.5: quick answers
Which is better, Muse Spark Open or Claude Opus 5.5?
It depends on what you measure. Claude Opus 5.5 scores higher than Muse Spark Open on all 5 public leaderboards that rate both. Claude Opus 5.5's widest lead is on Vals AI. On the ArtificialWatch Index, which takes the median of each model's percentile across the boards that score it, Muse Spark Open is at 16.7 and Claude Opus 5.5 at 90.9 (out of 100).
Which is newer, Muse Spark Open or Claude Opus 5.5?
Muse Spark Open. It went live on October 15, 2026, 23 days after Claude Opus 5.5 (September 22, 2026).
How do Muse Spark Open and Claude Opus 5.5 compare for coding?
On the ArtificialWatch coding index, Muse Spark Open is at 21.6 (#43 of 48) and Claude Opus 5.5 at 90 (#3). Claude Opus 5.5 scores higher on both coding boards that rate them.
Who makes Muse Spark Open and Claude Opus 5.5?
Muse Spark Open is from Meta; Claude Opus 5.5 is from Anthropic.
Where do these numbers come from?
Each score is the leaderboard's own published figure, read by ArtificialWatch (table composed November 13, 2026). Boards measure different things, so raw scores are only comparable within a row.
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