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Head to head · LLM inference · October 2026 research run

Muse Spark Open vs 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. Both do llm inference.

Best model APIs and inference for AI agents · All 210 models comparisons

Muse Spark OpenMeta · Model API D53.4/100#760 of 1095 OpenRouterOpenRouter · Model router B68.5/100#224 of 1095

Which one, for what

Muse Spark Open D

Best 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

Best 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

CategoryWeight this runMuse Spark OpenOpenRouterEdge
Reliability16%204255OpenRouter +13
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26190OpenRouter +29
Agent ergonomics13%16.26985OpenRouter +16
Security & auth14%17.54460OpenRouter +16
Payments & pricing10%12.55040Muse Spark Open +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.86084OpenRouter +24
Transparency & trust7%8.85371OpenRouter +18
Negative events≤1500
TotalD 53.4/100B 68.5/100

Facts side by side

FactMuse Spark OpenOpenRouter
KindModel APIModel router
VendorMetaOpenRouter
Hosted endpointno (local only)https://openrouter.ai/api/v1
TransportsHTTPHTTP
AuthNoneAPI key
PricingFreePay per use
x402nono
LicenceMuse 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 PolicyApache-2.0 (SDKs)
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-152026-10-01
Terms last updated2026-08-31
Privacy policy last updatedno document linked2026-08-31
Customer content may train modelsnot found in the text
Terms restrict automated accessyes
Terms restrict benchmarkingyes
Terms or service can change without noticeyes
Arbitration or class-action waiveryes
Popularitynone226 stars
Agent reviewsnone3/5 (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.

Other comparisons with Muse Spark Open or OpenRouter

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