Kimi K3 vs Muse Spark Open
Kimi K3 (2026) and Muse Spark Open (2026) are frontier-tier reasoning models from Moonshot AI and AI at Meta. Both ship a 1M-token context window. On Google-Proof Q&A, Kimi K3 leads by 4.5 pts. On pricing, Muse Spark Open costs $1.25/1M input tokens versus $3/1M for the alternative. This comparison covers specs, pricing, API access, capabilities, benchmarks, input and output token costs, and production fit for coding and agent workloads.
Muse Spark Open is ~140% cheaper at $1.25/1M; pay for Kimi K3 only for vision-heavy evaluation.
Decision scorecard
Local evidence first| Signal | Kimi K3 | Muse Spark Open |
|---|---|---|
| Best for | reasoning-heavy apps, multimodal apps, and tool-calling agents | reasoning-heavy apps, multimodal apps, and tool-calling agents |
| Decision fit | RAG, Agents, and Long context | Coding, RAG, and Agents |
| Context window | 1M | 1M |
| Cheapest output | $15/1M tokens | $4.25/1M tokens |
| Provider routes | 3 tracked | 4 tracked |
| Shared benchmarks | Google-Proof Q&A leader | 7 shared |
Decision tradeoffs
- Kimi K3 holds a shared-benchmark lead on Google-Proof Q&A, ahead by 4.5 points.
- Kimi K3 uniquely exposes Structured outputs in local model data.
- Local decision data tags Kimi K3 for RAG, Agents, and Long context.
- Muse Spark Open holds a shared-benchmark lead on Humanity's Last Exam — With Tools, ahead by 5 points.
- Muse Spark Open has the lower cheapest tracked output price at $4.25/1M tokens.
- Muse Spark Open has broader tracked provider coverage for fallback and route flexibility.
- Local decision data tags Muse Spark Open for Coding, RAG, and Agents.
Monthly cost at traffic
Estimate token spend from the cheapest tracked input and output route or tier on this page.
Kimi K3
$6,150
Cheapest tracked route/tier: Moonshot AI Kimi
Muse Spark Open
$2,063
Cheapest tracked route/tier: Together AI
Estimated monthly gap: $4,088. Batch, cache, alternate speed tiers, and negotiated pricing are excluded from this local estimate.
Switch friction
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Muse Spark Open is $10.75/1M tokens lower on cheapest tracked output pricing before cache, batch, or negotiated discounts.
- Check replacement coverage for Structured outputs before moving production traffic.
- Provider overlap exists on OpenRouter; start route-level A/B tests there.
- Kimi K3 is $10.75/1M tokens higher on cheapest tracked output pricing, so quality gains need to justify the spend.
- Kimi K3 adds Structured outputs in local capability data.
Specs
| Specification | ||
|---|---|---|
| Released | 2026-07-14 | 2026-10-15 |
| Context window | 1M | 1M |
| Parameters | 2.8T total; 16 of 896 experts active | 816B (42B activated) |
| Architecture | Mixture of Experts | Mixture of Experts |
| License | Kimi K3 License | Muse Model License |
| Openness | Open weights | Open weights |
| Weights | Available | Available |
| Code | Unknown | Unknown |
| Commercial use | Commercial use: conditional | Commercial use: conditional |
| Knowledge cutoff | - | - |
Pricing and availability
| Pricing attribute | Kimi K3 | Muse Spark Open |
|---|---|---|
| Input price | $3/1M tokens | $1.25/1M tokens |
| Output price | $15/1M tokens | $4.25/1M tokens |
| Providers |
Capabilities
| Capability | Kimi K3 | Muse Spark Open |
|---|---|---|
| Vision | Yes | Yes |
| Multimodal | Yes | Yes |
| Reasoning | Yes | Yes |
| JSON / Tool use | Yes | Yes |
| Structured outputs | Yes | No |
| Code execution | No | No |
| IDE integration | No | No |
| Computer use | No | No |
| Parallel agents | No | No |
Benchmarks
| Benchmark | Kimi K3 | Muse Spark Open |
|---|---|---|
| Google-Proof Q&A | 93.5 | 89.0 |
| Terminal-Bench 2.1 | 88.3 | 76.4 |
| DeepSWE 1.1 | 68.5 | 60.0 |
| Humanity's Last Exam — With Tools | 56.0 | 61.0 |
| MCP-Atlas | 84.2 | 89.2 |
| WorldVQA | 51.0 | 49.4 |
| Toolathlon | 73.2 | 72.8 |
Deep dive
On shared benchmark coverage, Google-Proof Q&A has Kimi K3 at 93.5 and Muse Spark Open at 89, with Kimi K3 ahead by 4.5 points; Terminal-Bench 2.1 has Kimi K3 at 88.3 and Muse Spark Open at 76.4, with Kimi K3 ahead by 11.9 points; DeepSWE 1.1 has Kimi K3 at 68.5 and Muse Spark Open at 60, with Kimi K3 ahead by 8.5 points. The largest visible gap is 11.9 points on Terminal-Bench 2.1, which matters most when that benchmark mirrors your workload. Treat isolated benchmark wins as directional, because provider routing, prompt style, and tool access can move real application results.
The capability footprint differs most on structured outputs: Kimi K3. Both models share vision, multimodal input, reasoning mode, and JSON / Tool use, so the practical split is not just feature count. Use those differences to decide whether the page is about raw model quality, agentic coding support, multimodal ingestion, or predictable structured API behavior.
For cost, Kimi K3 lists $3/1M input and $15/1M output tokens on the cheapest tracked provider, while Muse Spark Open lists $1.25/1M input and $4.25/1M output tokens on the cheapest tracked provider. A 70/30 input-output blend puts Muse Spark Open lower by about $4.45 per million blended tokens. Availability is 3 providers versus 4, so concentration risk also matters.
Choose Kimi K3 when vision-heavy evaluation are central to the workload. Choose Muse Spark Open when vision-heavy evaluation, lower input-token cost, and broader provider choice are more important. For production, rerun your own prompts through the exact provider, region, and tool stack you plan to ship.
FAQ
Which has a larger context window, Kimi K3 or Muse Spark Open?
Kimi K3 supports 1M tokens, while Muse Spark Open supports 1M tokens. That gap matters most for long documents, large codebases, retrieval-heavy agents, and conversations where earlier context must remain visible.
Which is cheaper, Kimi K3 or Muse Spark Open?
Muse Spark Open is cheaper on tracked token pricing. Kimi K3 costs $3/1M input and $15/1M output tokens. Muse Spark Open costs $1.25/1M input and $4.25/1M output tokens. Provider discounts or batch pricing can still change the final bill.
Is Kimi K3 or Muse Spark Open open source?
Kimi K3 is listed under Kimi K3 License. Muse Spark Open is listed under Muse Model License. License labels affect whether you can self-host, redistribute weights, or rely only on hosted APIs, so confirm the upstream license before deployment.
Which is better for vision, Kimi K3 or Muse Spark Open?
Both Kimi K3 and Muse Spark Open expose vision. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface. Use this as a quick comparison signal, then confirm the provider-specific limits before committing to production.
Which is better for multimodal input, Kimi K3 or Muse Spark Open?
Both Kimi K3 and Muse Spark Open expose multimodal input. The better choice depends on benchmark fit, context budget, pricing, and whether your provider route exposes the same capability surface.
Where can I run Kimi K3 and Muse Spark Open?
Kimi K3 is available on Moonshot AI Kimi, OpenRouter, and Featherless. Muse Spark Open is available on Together AI, Fireworks AI, GroqCloud, and OpenRouter. Provider coverage can affect latency, region availability, compliance posture, and fallback options.
Continue comparing
Last reviewed: 2026-10-16. Data sourced from public model cards and provider documentation.