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You use the facilitator from server-side middleware. Buyers usually should not call a hosted facilitator URL directly. They call your API, receive HTTP 402, sign a guarantee, and retry your protected route. That distinction matters because you own the commercial context: route, price, accepted networks, accepted assets, payTo address, logging, and abuse policy.

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URLs your service uses

URL typeWho calls itPurpose
Protected routeBuyer or buyer agentRequests the paid resource.
Facilitator APIYour middlewareVerifies and settles signed payment guarantees.
Core4Mica contractsPayer or seller through protocol operationsCollateral, settlement, claim, and withdrawal enforcement.

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Keep facilitator calls server-side

Server-side facilitator calls let you:
  • apply allowlists, blocklists, and rate limits;
  • attach request metadata for support and audit;
  • hide infrastructure details from buyers;
  • migrate facilitator deployments without changing your protected routes.

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Hosted facilitator

Hosted deployments commonly use: 
https://x402.4mica.xyz/
Use hosted or self-hosted facilitator URLs from your server configuration. Do not make buyers depend on those URLs directly unless you are intentionally exposing a lower-level integration.

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Operational guidance

  • Log every verification and settlement request with route, buyer, network, price, guarantee ID, and response.
  • Reject guarantees for routes, prices, assets, or networks you no longer accept.
  • Treat unexpected direct facilitator usage as an integration smell unless you explicitly documented it.