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HEAD TO HEAD · UPDATED NOV 6, 2026
Claude Opus 5.5 vs Muse Spark Open
Anthropic against Meta, on sourced numbers only. Green marks the higher (or cheaper) value on each row; the text below only calls a lead when the gap is bigger than measurement noise.
| Claude Opus 5.5 | Muse Spark Open | |
|---|---|---|
| Arena Elo | 1509 source ↗ | not published |
| GPQA Diamond | 90.6% source ↗ | 89.0% source ↗ |
| $ per 1M in / out | $4 / $20 source ↗ | $1.25 / $4.25 source ↗ |
| Blended $ per 1M (3:1) | $8.00 source ↗ | $2.00 source ↗ |
| Context window | 1M source ↗ | 1M source ↗ |
| Output speed | 110 tok/s source ↗ | 153 tok/s source ↗ |
| Released | Sep 22, 2026 source ↗ | Oct 15, 2026 source ↗ |
| Open weights | No source ↗ | Yes source ↗ |
| Reasoning effort tiers | low · medium · high · xhigh · max (default: medium) | not verified (default: not stated) |
| API effort control | output_config={"effort": "low" | "medium" | "high" | "xhigh" | "max"} source ↗ | Not verified: reasoning controls depend on the host source ↗ |
| Additional benchmarks | Arena WebDev: 1810 (#1) source ↗ SWE-bench Pro: 89.9% source ↗ Terminal-Bench 4.0: 66.4% (xhigh) source ↗ GDPval-AA v2.1: 1846 source ↗ CursorBench 4.0: 57.8% at max effort, 52.5% at default source ↗ AA Intelligence Index v5.0.1: 59 source ↗ | Size: 816B total, 42B active (MoE) source ↗ Output speed: 153 tok/s, varies by host source ↗ |
| Best for (workload) | Anthropic suggests starting with Opus 5.5 for most workloads. #1 on Arena WebDev (1810); 66.4% on Terminal-Bench 4.0 at xhigh effort (Anthropic). source ↗ | Meta's large open-weights model (816B total, 42B active) with a 1M context window; 89.0% GPQA Diamond (Meta). source ↗ |
Arena Elo from the arena.ai text leaderboard as of Oct 27, 2026 source ↗. Speed measured by Artificial Analysis and varies by provider.
Which one should I use?
For high-volume work where cost matters most, Muse Spark Open is about 4.0 times cheaper per token. For latency-sensitive use such as live chat, Muse Spark Open is noticeably faster (153 vs 110 tokens per second). If you need to self-host or fine-tune, only Muse Spark Open has open weights. On release timing, Anthropic is at day 30 of a typical ~15-day gap (PAST TYPICAL GAP), and Meta is at day 22 of a typical ~14-day gap (PAST TYPICAL GAP).
Key differences from the sourced numbers
- Muse Spark Open is the cheaper option: $2.00 vs $8.00 per 1M tokens at a 3:1 input-to-output mix (about 4.0 times less).
- On GPQA Diamond they are close (90.6% vs 89.0%).
- Muse Spark Open streams output faster: 153 vs 110 tokens per second (Artificial Analysis).
- Claude Opus 5.5 pricing note: Same rate across the full 1M context window.
- Muse Spark Open pricing note: Hosted price on OpenRouter (ID meta/muse-spark-open) and Together AI (ID meta-models/Muse-Spark-Open-816B-A42B). Open weights under the Muse Model License.
Frequently asked questions
Is Claude Opus 5.5 or Muse Spark Open better?
Muse Spark Open is the cheaper option: $2.00 vs $8.00 per 1M tokens at a 3:1 input-to-output mix (about 4.0 times less). On GPQA Diamond they are close (90.6% vs 89.0%). Muse Spark Open streams output faster: 153 vs 110 tokens per second (Artificial Analysis). Claude Opus 5.5 pricing note: Same rate across the full 1M context window. Muse Spark Open pricing note: Hosted price on OpenRouter (ID meta/muse-spark-open) and Together AI (ID meta-models/Muse-Spark-Open-816B-A42B). Open weights under the Muse Model License.
Which one should I use: Claude Opus 5.5 or Muse Spark Open?
For high-volume work where cost matters most, Muse Spark Open is about 4.0 times cheaper per token. For latency-sensitive use such as live chat, Muse Spark Open is noticeably faster (153 vs 110 tokens per second). If you need to self-host or fine-tune, only Muse Spark Open has open weights. On release timing, Anthropic is at day 30 of a typical ~15-day gap (PAST TYPICAL GAP), and Meta is at day 22 of a typical ~14-day gap (PAST TYPICAL GAP).
How much does Claude Opus 5.5 cost compared with Muse Spark Open?
Claude Opus 5.5 lists at $4 / $20 per 1M input/output tokens ($8.00/1M blended at 3:1). Muse Spark Open lists at $1.25 / $4.25 per 1M input/output tokens ($2.00/1M blended at 3:1).
Facts checked Nov 5, 2026 against official sources. Every number links to its source. Spotted an error? Email [email protected].