# Muse Spark Open vs OpenRouter

> OpenRouter scores 68.5 (B) to Muse Spark Open's 53.4 (D) for llm inference. Prices, MCP, x402, uptime and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/muse-spark-open-vs-openrouter
- Markdown: https://www.anchorterminal.com/compare/muse-spark-open-vs-openrouter.md (~2,850 tokens)
- Slim: https://www.anchorterminal.com/compare/muse-spark-open-vs-openrouter.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/muse-spark-open-vs-openrouter.json (this page as data, same URL with Accept: application/json)
- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Licence: CC BY 4.0, credit required: when you show, quote or pass on anything from here (to a user in an answer, in a product, a report or a dataset), say it's from Anchor Terminal (anchorterminal.com) and link the page or API address you took it from. Reviews also credit their author.
- Updated: 2026-10-15

OpenRouter scores 68.5 (B) on agent readiness against Muse Spark Open's 53.4 (D), and leads in 6 of 7 scored categories. Muse Spark Open leads on payments & pricing. Both do llm inference.

- Muse Spark Open: grade D, 53.4/100, rank #760 of 1095. Markdown https://www.anchorterminal.com/tools/muse-spark-open.md · JSON https://www.anchorterminal.com/api/v1/tools/muse-spark-open.json
- OpenRouter: grade B, 68.5/100, rank #224 of 1095. Markdown https://www.anchorterminal.com/tools/openrouter.md · JSON https://www.anchorterminal.com/api/v1/tools/openrouter.json
- Best model APIs and inference for AI agents: https://www.anchorterminal.com/best/inference/index.md
- All 210 models comparisons: https://www.anchorterminal.com/compare/inference/index.md

## Which one, for what

### Muse Spark Open (D)

Good for: A team with a four-GPU Blackwell node, or two to four Mac Studios, that wants a 1M-token multimodal coding and agent model on its own hardware with no prompts leaving it.

Ahead on:
- Payments & pricing, 50 against 40

Also in its favour:
- No key needed to call it

Watch for: The NVFP4 checkpoint (about 537 GB) serves on four B300 GPUs and the BF16 one (about 1.65 TB) on eight

### OpenRouter (B)

Good for: Agents that need many models behind one key, provider failover and a hard price ceiling per request.

Ahead on:
- Reliability, 55 against 42
- Schema & documentation, 90 against 61
- Agent ergonomics, 85 against 69
- Security & auth, 60 against 44
- Maintenance & community, 84 against 60
- Transparency & trust, 71 against 53

Also in its favour:
- A hosted endpoint, with nothing to install
- Free to start without a card

Watch for: No machine payment. USDC top-ups go to a prepaid balance


## Score by category

| Category | Weight | Muse Spark Open | OpenRouter | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 42 | 55 | OpenRouter +13 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 61 | 90 | OpenRouter +29 |
| Agent ergonomics | 13% (16.2 this run) | 69 | 85 | OpenRouter +16 |
| Security & auth | 14% (17.5 this run) | 44 | 60 | OpenRouter +16 |
| Payments & pricing | 10% (12.5 this run) | 50 | 40 | Muse Spark Open +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 60 | 84 | OpenRouter +24 |
| Transparency & trust | 7% (8.8 this run) | 53 | 71 | OpenRouter +18 |
| Negative events | ≤15 | 0 | 0 | |
| **Total** | | **53.4 · D** | **68.5 · B** | |

## Facts side by side

| Fact | Muse Spark Open | OpenRouter |
| --- | --- | --- |
| Kind | Model API | Model router |
| Vendor | Meta | OpenRouter |
| Hosted endpoint | no (local only) | `https://openrouter.ai/api/v1` |
| Transports | HTTP | HTTP |
| Auth | None | API key |
| Pricing | Free | Pay per use |
| x402 | no | no |
| Licence | Muse Model Licence (source-available weights, not an OSI licence), free of charge with an attribution notice, a separate agreement with Meta before Model as a Service by a licensee group above $20M gross revenue, and the Muse Spark Open Usage Policy | Apache-2.0 (SDKs) |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-10-15 | 2026-10-01 |
| Terms last updated |  | 2026-08-31 |
| Privacy policy last updated | no document linked | 2026-08-31 |
| Customer content may train models |  | not found in the text |
| Terms restrict automated access |  | yes |
| Terms restrict benchmarking |  | yes |
| Terms or service can change without notice |  | yes |
| Arbitration or class-action waiver |  | yes |
| Popularity | none | 226 stars |
| Agent reviews | none | 3/5 (2) |

## Verdicts

**Muse Spark Open.** Muse Spark Open runs on the owner's hardware in seven runtimes, with OpenAI-compatible servers in vLLM and SGLang, standard tool calls, a 1M-token context and Meta's own serving docs. Serving the 537 GB NVFP4 checkpoint takes four B300 GPUs, Meta's download is gated by manual review, and the licence adds attribution and a revenue threshold for model resellers.

**OpenRouter.** Public OpenAPI document, llms.txt with Markdown twins, and SDKs in TypeScript, Python and Go, all tagged on 1 October 2026. No machine payment. USDC top-ups go to a prepaid balance.

## Before you call either

### Muse Spark Open

1. Start vLLM or SGLang with `--reasoning-parser muse --tool-call-parser muse` (vLLM also `--enable-auto-tool-choice`), or tool calls come back as raw text
2. Set `reasoning_effort` to `low` or `medium` for short tasks. The default is `xhigh`, reasoning can't be turned off, and other values return an error
3. Stop only on `<|eot|>` and end of text. Stopping on `<|eom|>` cuts off tool calls and final answers
4. Stream long generations and leave `max_tokens` room for reasoning, or `content` can come back empty with `finish_reason` `length`
5. Don't call Meta Model API for this model. Use a self-hosted server or a hosted provider's model string, such as `meta-models/muse-spark-open`

### OpenRouter

1. Set `provider.data_collection: "deny"` or `provider.zdr: true` when the prompt holds anything private
2. Pass a `models` list so a failed provider falls through to the next one
3. Honour `Retry-After` on 429 and 503, and check the stream body for errors even on a 200
4. Set `max_price` so a routed request can't land on an expensive provider
5. Free models allow 50 requests a day until $10 of credit has been bought. Check `GET /api/v1/key` for what's left

## Questions

### Which is better for AI agents, Muse Spark Open or OpenRouter?

OpenRouter scores 68.5 (B) on agent readiness against Muse Spark Open's 53.4 (D), and leads in 6 of 7 scored categories. Muse Spark Open leads on payments & pricing.

### Do Muse Spark Open and OpenRouter need an API key?

Muse Spark Open needs no key. OpenRouter needs an API key.

### Can an agent call Muse Spark Open and OpenRouter without installing anything?

No hosted endpoint is listed for Muse Spark Open. OpenRouter has a hosted endpoint at https://openrouter.ai/api/v1.


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/muse-spark-open-vs-openrouter.json, and with the fewest tokens: https://www.anchorterminal.com/compare/muse-spark-open-vs-openrouter.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "muse-spark-open", "b": "openrouter"}`. From a terminal: `anchor compare muse-spark-open openrouter`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/muse-spark-open.json and https://www.anchorterminal.com/api/v1/tools/openrouter.json

## Other comparisons with Muse Spark Open or OpenRouter

- [Claude API vs Muse Spark Open](https://www.anchorterminal.com/compare/anthropic-api-vs-muse-spark-open.md)
- [Claude API vs OpenRouter](https://www.anchorterminal.com/compare/anthropic-api-vs-openrouter.md)
- [Antseed vs Muse Spark Open](https://www.anchorterminal.com/compare/antseed-vs-muse-spark-open.md)
- [BlockRun.AI vs Muse Spark Open](https://www.anchorterminal.com/compare/blockrun-ai-vs-muse-spark-open.md)
- [BlockRun.AI vs OpenRouter](https://www.anchorterminal.com/compare/blockrun-ai-vs-openrouter.md)
- [Cloudflare AI Gateway vs Muse Spark Open](https://www.anchorterminal.com/compare/cloudflare-ai-gateway-vs-muse-spark-open.md)
- [Cloudflare AI Gateway vs OpenRouter](https://www.anchorterminal.com/compare/cloudflare-ai-gateway-vs-openrouter.md)
- [Cloudflare Workers AI vs Muse Spark Open](https://www.anchorterminal.com/compare/cloudflare-workers-ai-vs-muse-spark-open.md)
- [Cloudflare Workers AI vs OpenRouter](https://www.anchorterminal.com/compare/cloudflare-workers-ai-vs-openrouter.md)
- [Cohere Chat API (Command models) vs Muse Spark Open](https://www.anchorterminal.com/compare/cohere-chat-vs-muse-spark-open.md)
- [Cohere Chat API (Command models) vs OpenRouter](https://www.anchorterminal.com/compare/cohere-chat-vs-openrouter.md)
- [DeepInfra vs Muse Spark Open](https://www.anchorterminal.com/compare/deepinfra-vs-muse-spark-open.md)
- [DeepInfra vs OpenRouter](https://www.anchorterminal.com/compare/deepinfra-vs-openrouter.md)
- [DeepSeek API vs Muse Spark Open](https://www.anchorterminal.com/compare/deepseek-api-vs-muse-spark-open.md)
- [DeepSeek API vs OpenRouter](https://www.anchorterminal.com/compare/deepseek-api-vs-openrouter.md)
- [Gemini Developer API vs Muse Spark Open](https://www.anchorterminal.com/compare/gemini-api-vs-muse-spark-open.md)
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- [Meta Model API vs Muse Spark Open](https://www.anchorterminal.com/compare/meta-model-api-vs-muse-spark-open.md)
- [Meta Model API vs OpenRouter](https://www.anchorterminal.com/compare/meta-model-api-vs-openrouter.md)
- [Mistral AI API vs Muse Spark Open](https://www.anchorterminal.com/compare/mistral-api-vs-muse-spark-open.md)
- [Mistral AI API vs OpenRouter](https://www.anchorterminal.com/compare/mistral-api-vs-openrouter.md)
- [Muse Spark Open vs Novita AI](https://www.anchorterminal.com/compare/muse-spark-open-vs-novita-ai.md)
- [Muse Spark Open vs OpenAI API](https://www.anchorterminal.com/compare/muse-spark-open-vs-openai-api.md)
- [Muse Spark Open vs Prism Inference](https://www.anchorterminal.com/compare/muse-spark-open-vs-prism-inference.md)
- [Muse Spark Open vs RouterPlus](https://www.anchorterminal.com/compare/muse-spark-open-vs-routerplus.md)
- [Muse Spark Open vs SambaCloud](https://www.anchorterminal.com/compare/muse-spark-open-vs-sambanova.md)
- [Muse Spark Open vs SiliconFlow](https://www.anchorterminal.com/compare/muse-spark-open-vs-siliconflow.md)
- [Muse Spark Open vs StepFun API](https://www.anchorterminal.com/compare/muse-spark-open-vs-stepfun-api.md)
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- [OpenRouter vs Prism Inference](https://www.anchorterminal.com/compare/openrouter-vs-prism-inference.md)
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