# Mellum2.1-12B-A2.5B-Thinking vs Muse Spark

> Side-by-side benchmark comparison for Mellum2.1-12B-A2.5B-Thinking and Muse Spark across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/mellum2-1-12b-a2-5b-thinking-vs-muse-spark
- Last updated: October 8, 2026

- Shared sourced benchmarks: 3
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

Evidence is too thin for a benchmark verdict: Mellum2.1-12B-A2.5B-Thinking and Muse Spark share only 3 sourced benchmark rows.

## Summary

- Only 3 shared sourced benchmark rows are available. That is not enough for a broad capability verdict, so this mirror does not name an overall winner.
- Muse Spark has the larger published context window at 262K.

## Model Snapshot

| Property | Mellum2.1-12B-A2.5B-Thinking | Muse Spark |
|----------|----------|----------|
| Creator | JetBrains | Meta |
| Type | Open Weight | Proprietary |
| Reasoning | Reasoning | Reasoning |
| Context | 128K | 262K |
| Independent public score (not head-to-head) | null | 59.97 |
| Benchmarks Covered | 7 | 27 |
| Pricing (input/output) | $0.00 / $0.00 | N/A |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 50.4 (Supported · #44/122)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.1 | 17.4% | Coming soon | Coming soon |
| Terminal-Bench 2.0 | Coming soon | 59% | Coming soon |
| τ²-bench results | Coming soon | 91.5% | Coming soon |
| DeepSearchQA | Coming soon | 74.8% | Coming soon |
| CyberGym | Coming soon | 43.5% | Coming soon |
| Claw-Eval | Coming soon | 63.8% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 50.7 (Supported · #40/146)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 82.0% | Coming soon | Coming soon |
| SWE-bench Verified | 47% | 77.4% | Muse Spark |
| SWE-bench Pro | 28% | 52.4% | Muse Spark |
| LiveCodeBench Pro | Coming soon | 80.0% | Coming soon |
| Vibe Code Bench | Coming soon | 19.67% | Coming soon |
| SWE-bench (Vals) | Coming soon | 74.4% | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 53.4 (Unranked · 3 rankable rows)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| ARC-AGI-2 | Coming soon | 42.5% | Coming soon |

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 78.5 (#14/49)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| CharXiv | Coming soon | 86.4% | Coming soon |
| MMMU-Pro | Coming soon | 80.4% | Coming soon |
| ERQA | Coming soon | 64.7% | Coming soon |
| SimpleVQA | Coming soon | 71.3% | Coming soon |
| ScreenSpot Pro | Coming soon | 84.1% | Coming soon |
| ZeroBench | Coming soon | 33.0% | Coming soon |
| MedXpertQA (MM) | Coming soon | 78.4% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 60.3 (Supported · #41/174)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 87.8% | Coming soon | Coming soon |
| GPQA-D | 64.6% | 89.5% | Muse Spark |
| HLE | Coming soon | 50.4% | Coming soon |
| HLE w/o tools | Coming soon | 42.8% | Coming soon |
| HealthBench Hard | Coming soon | 42.8% | Coming soon |
| MedXpertQA (Text) | Coming soon | 52.6% | Coming soon |
| GPQA Diamond (Vals) | Coming soon | 89.6% | Coming soon |
| MMLU-Pro (Vals) | Coming soon | 87.3% | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 91.9 (#8/125)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 90.6% | Coming soon | Coming soon |

### Mathematics

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark public-lane score: 55.1 (Unranked · 2 rankable rows)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark | Winner |
|-----------|-----------|-----------|--------|
| FrontierMath v2 (Tiers 1-3) | Coming soon | 39.000% | Coming soon |
| FrontierMath v2 (Tier 4) | Coming soon | 14.600% | Coming soon |

## FAQ

### Is there enough evidence to pick between Mellum2.1-12B-A2.5B-Thinking and Muse Spark?

Not yet. The models share only 3 sourced benchmark rows, so this mirror reports the available measurements and metadata without naming a broad winner.

### What can I compare safely on this page?

Published pricing, context windows, model type, and individual shared benchmark rows are directly comparable. Independent overall scores and non-overlapping benchmark coverage are labeled separately and should not be read as a controlled head-to-head result.

## Related Comparisons

- [Mellum2.1-12B-A2.5B-Thinking vs Muse Spark 1.2](/compare/mellum2-1-12b-a2-5b-thinking-vs-muse-spark-1-2)
- [Muse Spark vs Muse Spark 1.2](/compare/muse-spark-vs-muse-spark-1-2)
- [Mellum2.1-12B-A2.5B-Thinking vs Muse Spark 1.1](/compare/mellum2-1-12b-a2-5b-thinking-vs-muse-spark-1-1)
- [Muse Spark vs Muse Spark 1.1](/compare/muse-spark-vs-muse-spark-1-1)

## Explore More

- [Mellum2.1-12B-A2.5B-Thinking profile](/models/mellum2-1-12b-a2-5b-thinking)
- [Muse Spark profile](/models/muse-spark)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)