Run Crossref DOI metadata enrichment.

API Acre verifies the exact x402 price, Base network, recipient, and request before any wallet opens. One successful call costs $0.003 USDC.

No accountNo subscriptionNo private-key uploadOne-call authorization

API Acre never receives your private key; signing stays inside your wallet.

Loading a no-payment verification…

Verified live x402 quote

1 · Choose how to run one call

Both routes use this exact verified request and one-call price. Nothing is connected, signed, installed, or paid until you continue.

Browser or mobile

Pay with a wallet

Use an installed EVM wallet, or open Coinbase Wallet through a desktop QR code or mobile handoff.

Agent or terminal

Use Coinbase Agentic Wallet

Copy a command locked to this endpoint, request, and exact USDC cap. Copying is inert; running it may install the official CLI and pay after its authentication and policy checks.

Review Coinbase docs

Network
Recipient
USDC contract

No ETH gas needed. Connecting does not sign or pay. This EIP-3009 payment needs only the displayed USDC on Base because the facilitator submits settlement. Reject any later prompt that differs from the verified amount or recipient.

Review exact-cap Coinbase command

Running this command may automatically spend up to $0.003 USDC. npx --yes approves package installation. Use a separate low-value wallet and review the verified request first.

npx --yes awal@latest x402 pay https://apiacre.com/v1/research/crossref-doi-metadata \
  -X POST \
  -d '{"doi":"10.1038/s41586-021-03819-2"}' \
  --max-amount 3000 \
  --json

Alternative third-party AgentCash command

The first command checks without paying; running fetch may pay up to the same exact cap.

Review AgentCash docs

npx --yes agentcash@latest check https://apiacre.com/v1/research/crossref-doi-metadata
npx --yes agentcash@latest fetch https://apiacre.com/v1/research/crossref-doi-metadata \
  --method POST \
  --header 'content-type: application/json' \
  --body '{"doi":"10.1038/s41586-021-03819-2"}' \
  --payment-protocol x402 \
  --payment-network base \
  --max-amount 0.003

See the result before connecting · Curated static example

Crossref DOI metadata enrichment returns structured JSON. This example is static; the paid call returns a fresh result and settlement receipt.

{
  "request_id": "018f1f54-7f38-7ba2-8dc3-5f90272d9f1a",
  "service": "research.crossref-doi-metadata",
  "version": "1",
  "data": {
    "doi": "10.1038/s41586-021-03819-2",
    "status": "matched",
    "work": {
      "doi": "10.1038/s41586-021-03819-2",
      "title": "Example normalized DOI record",
      "type": "journal-article",
      "publishedDate": "2021-08-25",
      "authors": [],
      "publisher": "Springer Science and Business Media LLC",
      "containerTitle": "Nature",
      "subjects": [],
      "language": "en",
      "doiUrl": "https://doi.org/10.1038/s41586-021-03819-2",
      "resourceUrl": "https://api.crossref.org/works/10.1038%2Fs41586-021-03819-2",
      "referenceCount": 0,
      "citedByCount": 0,
      "issn": [],
      "isbn": [],
      "licenses": [],
      "updates": []
    },
    "source": "https://api.crossref.org/works/10.1038%2Fs41586-021-03819-2",
    "retrievedAt": "2026-08-20T12:00:00+00:00",
    "documentation": "https://www.crossref.org/documentation/retrieve-metadata/rest-api/",
    "metadataLicense": {
      "name": "Open bibliographic metadata / Crossref-generated data CC0",
      "url": "https://www.crossref.org/documentation/retrieve-metadata/",
      "abstractsReturned": false
    },
    "limitations": [
      "Demonstration metadata only; paid calls return the current DOI record.",
      "Abstracts and full text are deliberately excluded."
    ]
  },
  "meta": {
    "duration_ms": 42,
    "cached": false,
    "sources": [],
    "warnings": [],
    "next_actions": []
  }
}

Review exact request JSON

Result

Settlement receipt

Independent monitoring

Live x402 handshake report

The x402 Register independently checks API Acre's unpaid challenge, price, protocol version, and availability. It does not purchase or validate paid results.

Open the current report ↗

Change the request (optional)

JSON input

The default request is verified automatically. Editing it invalidates the quote and requires this no-payment verification again.

Prefer your own client? Use the official x402 SDK examples. Browser checkout requires an EVM wallet with USDC on Base; command-line buyers require their own separately configured wallet and spending policy.