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DEV Community· ScriptMasterLabs·· 2 小時前AI 評分43

AI 智能體貨幣換算 API：採用 ECB 參考匯率，按次付費

Currency Conversion API for AI Agents: ECB Reference Rates, Pay Per Conversion

AI 導讀

SML FX Convert 為 AI 智能體提供按次付費換算，採用歐洲央行每日參考匯率，每筆獲接受的換算收費 $0.001 USDC（Base mainnet）。服務毋須 API key 或帳戶，未付款請求會收到 HTTP 402 及 PAYMENT-REQUIRED 標頭。匯率不可用時不會結算；這是 ECB 參考匯率計算，並非可執行報價。

正文

ScriptMasterLabs

Agent workflows price, report, and budget in more than one currency. The usual routes to a conversion are a subscription FX feed, another API key to babysit, or pretending a reference rate is a tradable quote. SML FX Convert is the pay-per-call primitive instead — with the source named up front.

Measured live on 2026-10-19

  • GET /api/fx/info (free) identifies the source in the response itself: European Central Bank EXR daily reference rates — "Source: ECB statistics." Price: $0.001 USDC per accepted conversion on Base mainnet.
  • GET /api/fx/convert?from=USD&to=EUR&amount=100 without payment → HTTP 402 with a PAYMENT-REQUIRED header quoting exactly 1,000 atomic USDC, network eip155:8453, scheme exact. No SML API key. No account. The 402 challenge is the entire checkout.
  • A 100-conversion credit pack runs 0.005 USDC — 0.00005 USDC per successful conversion when fully used.
  • Fail-closed by contract: "No real rate => no settlement; caller receives a free alternative route." Invalid codes, malformed amounts, or unavailable reference data are never silently transformed into a paid, fabricated conversion.

The honest limit

This is an ECB reference-rate calculation — not a bank, card, exchange, or broker execution quote. It does not custody fiat, trade currencies, guarantee a spread, or promise that a reference rate is executable anywhere. What it is for: normalizing vendor prices, comparing API costs quoted in different currencies, converting budget limits before tool selection, and keeping agent-commerce reporting in a single reference currency — where source provenance matters more than pretending a reference rate is a live dealing price.

Fresh x402 target terms remain authoritative immediately before spend; a 402 challenge is not settlement, and settlement is not acceptance.

Full evidence and claim receipts: the canonical link on this article.

來源：DEV Community · dev.to

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