Kimi K3 vs Muse Spark Open
Kimi K3 leads Muse Spark Open on coding, 62.3 to 47.4 on the Vibe Coding Index, and Muse Spark Open costs 3.5x less per output token ($4.25 vs $15.00 per million). Updated October 22, 2026; 28 benchmarks have a result for both.
Kimi K3 or Muse Spark Open: which to pick
Pick Kimi K3 for coding: it scores 62.3 on the Vibe Coding Index against 47.4 for Muse Spark Open.
Pick Muse Spark Open for output tokens 3.5x cheaper ($4.25 vs $15.00 per million) and work measured by LiveBench coding or Code migration (Vals AI), where it leads.
- Shared results
- 28
- Kimi K3 only
- 89
- Muse Spark Open only
- 0
- Like-for-like categories
- 6 of 9
Only benchmarks that tested both models count toward a pick; a result only one model has is shown but not compared.
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, six public coding benchmarks
Kimi K3
Kimi K3 scores 62.3 against 47.4.
6 and 4 benchmarks behind the scores
Intelligence
AA Intelligence Index
No call
Only Kimi K3 has a AA Intelligence Index result, 43.6.
Directional only
Agentic work
AA Agentic Index
No call
Only Kimi K3 has a AA Agentic Index result, 50.0.
Directional only
Reasoning
GPQA Diamond
No call
Only Kimi K3 has a GPQA Diamond result, 92.9%.
Directional only
Knowledge
MMLU Pro
No call
Only Kimi K3 has a MMLU Pro result, 88.0%.
Directional only
Web design
Design Arena: websites
Kimi K3
Kimi K3 leads, 1334 against 1310.
Same board, both measured
General
Vals Index
Kimi K3
Kimi K3 leads, 53.0% against 48.6%.
Same board, both measured
Long documents
Listed context window
No call
Both take 1.05M tokens.
Listed by OpenRouter
Everyday cost
1K input + 500 output tokens
Muse Spark Open
Kimi K3 $0.011, Muse Spark Open $0.0034 per turn.
List prices
Cost per solved task
One SWE-bench Verified task, solved
No call
Only Kimi K3 has the number, $0.81.
Directional only
At a glance
- Coding index
- Kimi K3 62.3 from 6 benchmarks, Muse Spark Open 47.4 from 4 benchmarks.
- Widest category
- Agentic work, 12.0 points apart on average over 9 shared benchmarks.
- Widest single gap
- LiveBench long agentic: Kimi K3 42.8% against Muse Spark Open 18.9%, 23.9 points apart on a 0 to 100 scale.
- Output price
- Kimi K3 $15.00 against Muse Spark Open $4.25 per million output tokens, 3.5x apart.
- Context window
- Both take 1.05M tokens.
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 | Kimi K3 | Bars | Muse Spark Open | Ties |
|---|---|---|---|---|
| Coding | 6 | 3 | ||
| Intelligence | 1 | 0 | ||
| Agentic work | 5 | 4 | ||
| Reasoning | 3 | 0 | ||
| Web design | 3 | 0 | ||
| General | 3 | 0 | ||
| All shared boards | 21 | 7 |
CodingLike-for-likeSix of these boards feed the Vibe Coding Index63
| Benchmark | Kimi K3 | Muse Spark Open | Leader |
|---|---|---|---|
| LiveBench coding | 59.3% | 73.6% | Muse Spark Open |
| LMArena WebDev | 1655 | 1528 | Kimi K3 |
| AA Coding Index | 76.2 | Not measured | Only Kimi K3 measured |
| LiveCodeBench (Vals AI) | 87.2% | Not measured | Only Kimi K3 measured |
| SWE-bench Verified (Vals AI) | 93.4% | Not measured | Only Kimi K3 measured |
| Terminal-Bench 4 (Vals AI) | 17.2% | 6.6% | Kimi K3 |
| Vibe Code Bench (Vals AI) | 85.0% | 76.2% | Kimi K3 |
| Code migration (Vals AI) | 16.1% | 21.2% | Muse Spark Open |
| ProgramBench (Vals AI) | 2.0% | Not measured | Only Kimi K3 measured |
| IOI (Vals AI) | 48.9% | Not measured | Only Kimi K3 measured |
| Terminal-Bench 2.1 (Vals AI) | 80.9% | Not measured | Only Kimi K3 measured |
| SWE-bench Multimodal (Vals AI) | 44.2% | Not measured | Only Kimi K3 measured |
| Vibe Code Bench 1-100 (Vals AI) | 18.2% | Not measured | Only Kimi K3 measured |
| CyberBench (Vals AI) | 75.2% | Not measured | Only Kimi K3 measured |
| SciCode | 59.5% | 58.4% | Kimi K3 |
| FrontierCode | 44.2% | Not measured | Only Kimi K3 measured |
| FrontierSWE | 25.9% | Not measured | Only Kimi K3 measured |
| WeirdML | 82.6% | Not measured | Only Kimi K3 measured |
| ALE-Bench | 1524.5 | 1590.1 | Muse Spark Open |
| LMArena Text: coding | 1508 | Not measured | Only Kimi K3 measured |
| LMArena Text: software and IT | 1499 | Not measured | Only Kimi K3 measured |
| LMArena WebDev: React | 1670 | 1529 | Kimi K3 |
| LMArena WebDev: HTML | 1644 | 1495 | Kimi K3 |
| LMArena WebDev: from an image | 1579 | Not measured | Only Kimi K3 measured |
| Neither model has a result on the other 15 boards here | |||
IntelligenceLike-for-likePublic boards, shown as published, kept out of the index10
| Benchmark | Kimi K3 | Muse Spark Open | Leader |
|---|---|---|---|
| AA Intelligence Index | 43.6 | Not measured | Only Kimi K3 measured |
| Epoch Capabilities Index | 157.9 | 155.1 | Kimi K3 |
Agentic workLike-for-likePublic boards, shown as published, kept out of the index54
| Benchmark | Kimi K3 | Muse Spark Open | Leader |
|---|---|---|---|
| AA Agentic Index | 50.0 | Not measured | Only Kimi K3 measured |
| Design Arena: agents building web apps | 1295 | Not measured | Only Kimi K3 measured |
| Design Arena: agents building full-stack apps | 1315 | Not measured | Only Kimi K3 measured |
| Design Arena: agents building mobile apps | 1269 | Not measured | Only Kimi K3 measured |
| Design Arena: agents building Android apps | 1253 | Not measured | Only Kimi K3 measured |
| Design Arena: agents building Godot games | 1223 | Not measured | Only Kimi K3 measured |
| Design Arena: agents building games | 1252 | Not measured | Only Kimi K3 measured |
| Design Arena: HTML slides | 1206 | Not measured | Only Kimi K3 measured |
| Design Arena: PowerPoint slides | 1247 | Not measured | Only Kimi K3 measured |
| Design Arena: spreadsheets | 1070 | Not measured | Only Kimi K3 measured |
| LiveBench research | 79.0% | 80.3% | Muse Spark Open |
| LiveBench browser | 16.0% | 36.0% | Muse Spark Open |
| LiveBench long agentic | 42.8% | 18.9% | Kimi K3 |
| Finance Agent (Vals AI) | 53.1% | 61.3% | Muse Spark Open |
| Tax Agent Bench (Vals AI) | 33.4% | 26.3% | Kimi K3 |
| Legal Research Bench (Vals AI) | 46.1% | 38.5% | Kimi K3 |
| Harvey's Legal Agent Benchmark (Vals AI) | 12.9% | 25.0% | Muse Spark Open |
| Excel Modeling Benchmark (Vals AI) | 66.7% | 53.7% | Kimi K3 |
| BioMysteryBench (Vals AI) | 72.6% | Not measured | Only Kimi K3 measured |
| Terminal-Bench-Science (Vals AI) | 1.4% | Not measured | Only Kimi K3 measured |
| Time Horizon Index (Vals AI) | 10.5% | Not measured | Only Kimi K3 measured |
| APEX-Agents | 47.8% | 33.4% | Kimi K3 |
| PostTrainBench | 32.0% | Not measured | Only Kimi K3 measured |
| Vending-Bench 2 | $5,165 | Not measured | Only Kimi K3 measured |
| Neither model has a result on the other 17 boards here | |||
ReasoningLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Kimi K3 | Muse Spark Open | Leader |
|---|---|---|---|
| GPQA Diamond | 92.9% | Not measured | Only Kimi K3 measured |
| LiveBench reasoning | 90.7% | 73.7% | Kimi K3 |
| MMMU Pro (Vals AI) | 88.2% | Not measured | Only Kimi K3 measured |
| GPQA Diamond (Artificial Analysis run) | 93.5% | 89.0% | Kimi K3 |
| Humanity's Last Exam (Artificial Analysis run) | 46.9% | 43.9% | Kimi K3 |
| GPQA Diamond (Epoch AI run) | 93.1% | Not measured | Only Kimi K3 measured |
| ARC-AGI | 94.5% | Not measured | Only Kimi K3 measured |
| ARC-AGI-2 | 60.4% | Not measured | Only Kimi K3 measured |
| SimpleBench | 60.7% | Not measured | Only Kimi K3 measured |
| Chess puzzles | 37.0% | Not measured | Only Kimi K3 measured |
| Mystery game puzzles | 26.0% | Not measured | Only Kimi K3 measured |
| LMArena Text: hard prompts | 1495 | Not measured | Only Kimi K3 measured |
| LMArena Text: expert | 1520 | Not measured | Only Kimi K3 measured |
| LMArena Text: hard prompts in English | 1496 | Not measured | Only Kimi K3 measured |
| Neither model has a result on the other 8 boards here | |||
MathDirectional onlyPublic boards, shown as published, kept out of the index6 boards, none shared
| Benchmark | Kimi K3 | Muse Spark Open | Leader |
|---|---|---|---|
| OTIS Mock AIME | 97.2% | Not measured | Only Kimi K3 measured |
| FrontierMath, tiers 1 to 3 | 72.2% | Not measured | Only Kimi K3 measured |
| FrontierMath, tier 4 | 39.0% | Not measured | Only Kimi K3 measured |
| ProofBench | 87.0% | Not measured | Only Kimi K3 measured |
| LMArena Text: math | 1494 | Not measured | Only Kimi K3 measured |
| LMArena Text: mathematical work | 1505 | Not measured | Only Kimi K3 measured |
| Neither model has a result on the other 7 boards here | |||
KnowledgeDirectional onlyPublic boards, shown as published, kept out of the index11 boards, none shared
| Benchmark | Kimi K3 | Muse Spark Open | Leader |
|---|---|---|---|
| MMLU Pro | 88.0% | Not measured | Only Kimi K3 measured |
| LegalBench (Vals AI) | 86.2% | Not measured | Only Kimi K3 measured |
| CorpFin (Vals AI) | 71.6% | Not measured | Only Kimi K3 measured |
| TaxEval (Vals AI) | 75.7% | Not measured | Only Kimi K3 measured |
| MortgageTax (Vals AI) | 66.3% | Not measured | Only Kimi K3 measured |
| MedCode (Vals AI) | 49.4% | Not measured | Only Kimi K3 measured |
| SimpleQA Verified | 50.6% | Not measured | Only Kimi K3 measured |
| LMArena Text: science | 1508 | Not measured | Only Kimi K3 measured |
| LMArena Text: medicine and healthcare | 1489 | Not measured | Only Kimi K3 measured |
| LMArena Text: legal and government | 1503 | Not measured | Only Kimi K3 measured |
| LMArena Text: business and finance | 1470 | Not measured | Only Kimi K3 measured |
| Neither model has a result on the other 7 boards here | |||
Web designLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Kimi K3 | Muse Spark Open | Leader |
|---|---|---|---|
| Design Arena: websites | 1334 | 1310 | Kimi K3 |
| Design Arena: UI components | 1341 | Not measured | Only Kimi K3 measured |
| Design Arena: game dev | 1358 | 1282 | Kimi K3 |
| Design Arena: data viz | 1351 | Not measured | Only Kimi K3 measured |
| Design Arena: 3D | 1387 | Not measured | Only Kimi K3 measured |
| Design Arena: all code categories | 1360 | Not measured | Only Kimi K3 measured |
| Design Arena: SVG | 1302 | Not measured | Only Kimi K3 measured |
| LiveBench design | 77.2% | 60.3% | Kimi K3 |
| Neither model has a result on the other 1 board here | |||
GeneralLike-for-likePublic boards, shown as published, kept out of the index30
| Benchmark | Kimi K3 | Muse Spark Open | Leader |
|---|---|---|---|
| Vals Index | 53.0% | 48.6% | Kimi K3 |
| LiveBench data analysis | 78.7% | 60.2% | Kimi K3 |
| Public Benefits Bench (Vals AI) | 68.2% | Not measured | Only Kimi K3 measured |
| SAGE (Vals AI) | 52.8% | Not measured | Only Kimi K3 measured |
| MedScribe (Vals AI) | 88.0% | Not measured | Only Kimi K3 measured |
| Vals Multimodal Index | 73.4% | Not measured | Only Kimi K3 measured |
| Long context reasoning (AA-LCR) | 88.7% | 78.3% | Kimi K3 |
| DTBench | 91.2% | Not measured | Only Kimi K3 measured |
| LMCA | 52.7% | Not measured | Only Kimi K3 measured |
| Surface Evolver Bench | 95.0% | Not measured | Only Kimi K3 measured |
| Furniture assembly | 34.2% | Not measured | Only Kimi K3 measured |
| LMArena Text | 1476 | Not measured | Only Kimi K3 measured |
| LMArena Text: instruction following | 1485 | Not measured | Only Kimi K3 measured |
| LMArena Text: creative writing | 1457 | Not measured | Only Kimi K3 measured |
| LMArena Text: English | 1481 | Not measured | Only Kimi K3 measured |
| LMArena Text: non-English | 1466 | Not measured | Only Kimi K3 measured |
| LMArena Text: Chinese | 1529 | Not measured | Only Kimi K3 measured |
| LMArena Text: German | 1490 | Not measured | Only Kimi K3 measured |
| LMArena Text: Japanese | 1494 | Not measured | Only Kimi K3 measured |
| LMArena Text: Korean | 1460 | Not measured | Only Kimi K3 measured |
| LMArena Text: French | 1492 | Not measured | Only Kimi K3 measured |
| LMArena Text: Spanish | 1472 | Not measured | Only Kimi K3 measured |
| LMArena Text: Russian | 1485 | Not measured | Only Kimi K3 measured |
| LMArena Text: Polish | 1458 | Not measured | Only Kimi K3 measured |
| LMArena Text: multi-turn | 1489 | Not measured | Only Kimi K3 measured |
| LMArena Text: longer queries | 1494 | Not measured | Only Kimi K3 measured |
| LMArena Text: writing and language | 1471 | Not measured | Only Kimi K3 measured |
| LMArena Text: entertainment and media | 1453 | Not measured | Only Kimi K3 measured |
| Neither model has a result on the other 18 boards here | |||
Image generationNot comparablePublic boards, shown as published, kept out of the index0 boards, none shared
| Benchmark | Kimi K3 | 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
Muse Spark Open costs less
Repository review
50K input + 3K output tokens
Muse Spark Open costs less
Agent loop
200K input + 10K output tokens
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 | MoonshotAI Kimi K3 | Meta Muse Spark Open |
|---|---|---|
| Maker | Moonshot AI | Meta |
| Weights | Open weights | Open weights |
| Released | July 16, 2026 | October 15, 2026 |
| Context window | 1.05M | 1.05M |
| Input $/Mtok | $3.00 | $1.25 |
| Output $/Mtok | $15.00 | $4.25 |
| Coding index | 62.3 | 47.4 |
| Independent measurements behind it | 6 | 4 |
| Cost per solved task | $0.81 | Not computable |
| Source | OpenRouter listing | OpenRouter listing |
Questions
Is Kimi K3 better than Muse Spark Open for coding?
Pick Kimi K3 for coding: it scores 62.3 on the Vibe Coding Index against 47.4 for Muse Spark Open. Pick Muse Spark Open for output tokens 3.5x cheaper ($4.25 vs $15.00 per million) and work measured by LiveBench coding or Code migration (Vals AI), where it leads.
Which is cheaper, Kimi K3 or Muse Spark Open?
Kimi K3 costs $3.00 per million input tokens and $15.00 per million output tokens; Muse Spark Open costs $1.25 and $4.25. Cost per solved task is known for Kimi K3 only.
Which has the bigger context window, Kimi K3 or Muse Spark Open?
Neither: both take 1.05M tokens.
How many benchmarks is the Kimi K3 vs Muse Spark Open comparison based on?
28 benchmarks have a result for both models as of October 22, 2026. Kimi K3's coding index rests on 6 independent benchmarks and Muse Spark Open's on 4. Where only one model has a result, the page says so instead of naming a winner.