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x402 lets you pay per run with a crypto wallet (USDC) instead of a prepaid Monid workspace balance. Your client signs an on-chain USDC payment in response to an HTTP 402 Payment Required, and Monid settles it via a facilitator. No workspace, no budget, no top-ups — payment is collected on-chain, per run.
x402 covers execution and retrieval only. Discovery and inspection still require a normal Monid API key — see What the API key is still for.

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Prerequisites

  • An x402-compatible client (e.g. @x402/fetch).
  • A wallet funded with USDC and native gas on your chosen network (see below).

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Supported networks

Monid advertises every supported network in its 402 accepts array. Your client picks by matching the network it wants — don’t blindly take accepts[0].
Minimum price: $0.01. Monid raises the advertised price to this floor if the run’s quote is lower.Metered endpoints (time-billed) are not available on x402 — x402 is a single fixed upfront payment.

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Execute a run

Instead of running with the CLI:
Use an x402-compatible client to POST to https://x402.monid.ai/v1/run:
The client handles the payment handshake for you: it receives the 402, signs a USDC authorization, retries the request, and returns the run body once the payment is settled and the run completes. input may carry { body, queryParams, pathParams } — the same shape as the standard /v1/run endpoint.

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Response

  • 200 — run completed. Body includes runId, provider, endpoint, status, output, providerResponse, price, billing, billedUnits, and pollUrl. The HTTP status mirrors the provider’s own status.
  • 408 — TIMED_OUT. Zero-billed.
  • 400 — invalid input, or an unsupported (metered) endpoint.
Save the runId and pollUrl from every response — you’ll need them to retrieve results later.

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Retrieve a run

Instead of getting a run with the CLI:
Use an x402-compatible client to GET the pollUrl returned by the pay response:
This route requires no payment — just a Sign-In-With-X (SIWX) signature from the same wallet that paid for the run. Your x402 client handles the SIWX challenge automatically.

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Response

  • 200 — run status and full body (output, providerResponse, price, cost, timestamps).
  • 401 — signature invalid.
  • 403 — you are not the wallet that paid for this run.
  • 404 — run not found.

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List runs

x402 does not support listing runs. Access control is per-run wallet ownership, and there’s no workspace to scope a list to. Retain each runId / pollUrl from your pay responses to retrieve them later. If you need to list runs, use the workspace-scoped GET /v1/runs with an API key.

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What the API key is still for

Even as an x402 user, you need a Monid API key for discovery, inspection, and listing runs. Typical loop: discover / inspect with your API key → pay and run with x402 → retrieve with x402.

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Next steps