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

> Side-by-side benchmark comparison for Mellum2.1-12B-A2.5B-Thinking and Muse Spark Open 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-open
- Last updated: October 15, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5.8

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for Mellum2.1-12B-A2.5B-Thinking and Muse Spark Open.

## Summary

- Mellum2.1-12B-A2.5B-Thinking and Muse Spark Open do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | Mellum2.1-12B-A2.5B-Thinking | Muse Spark Open |
|----------|----------|----------|
| Creator | JetBrains | Meta |
| Type | Open Weight | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 128K | 1M |
| Independent public score (not head-to-head) | null | 62.66 |
| Benchmarks Covered | 7 | 7 |
| Pricing (input/output) | $0.00 / $0.00 | Pricing unavailable / Pricing unavailable |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark Open public-lane score: 60.2 (Estimated · #27/127)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark Open | Winner |
|-----------|-----------|-----------|--------|
| Terminal-Bench 2.1 | 17.4% | Coming soon | Coming soon |
| JobBench | Coming soon | 61.8% | Coming soon |
| MCP Atlas | Coming soon | 89.2% | Coming soon |
| HLE w/ tools | Coming soon | 61.0% | Coming soon |
| Toolathlon-Verified | Coming soon | 72.8% | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark Open public-lane score: 56.1 (Supported · #29/150)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark Open | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 82.0% | Coming soon | Coming soon |
| SWE-bench Verified | 47% | Coming soon | Coming soon |
| SWE-bench Pro | 28% | Coming soon | Coming soon |

### Reasoning

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark Open public-lane score: 79.6 (Unranked · 2 rankable rows)

### Multimodal & Grounded

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark Open public-lane score: 83.6 (Unranked · 4 rankable rows)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark Open | Winner |
|-----------|-----------|-----------|--------|
| ZeroBench | Coming soon | 50.0% | Coming soon |
| BabyVision | Coming soon | 80.2% | Coming soon |
| SimpleVQA | Coming soon | 73.6% | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark Open public-lane score: 64.6 (Supported · #38/184)

| Benchmark | Mellum2.1-12B-A2.5B-Thinking | Muse Spark Open | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 87.8% | Coming soon | Coming soon |
| GPQA-D | 64.6% | Coming soon | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Mellum2.1-12B-A2.5B-Thinking public-lane score: Coming soon
- Muse Spark Open public-lane score: Coming soon

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

## FAQ

### Can I compare Mellum2.1-12B-A2.5B-Thinking and Muse Spark Open on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [Mellum2.1-12B-A2.5B-Thinking vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-mellum2-1-12b-a2-5b-thinking)
- [Muse Spark Open vs Claude Opus 5.5](/compare/claude-opus-5-5-vs-muse-spark-open)
- [Mellum2.1-12B-A2.5B-Thinking vs GPT-6.1 Sol](/compare/gpt-6-1-sol-vs-mellum2-1-12b-a2-5b-thinking)
- [Muse Spark Open vs GPT-6.1 Sol](/compare/gpt-6-1-sol-vs-muse-spark-open)

## Explore More

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