Currency exchange rate and conversion API

$0.01 per call · failed calls are never charged · no account or subscription: pay per call with a card key or USDC

Foreign exchange rates from the European Central Bank for about 30 major currencies (USD, EUR, GBP, JPY, CHF, SEK, CAD, AUD, CNY, INR, BRL and more). Give a base currency, optionally the target currencies and an amount, and get the rates, the converted amounts and the date the rates apply to. Use for currency conversion, invoice and price calculations, and reporting in another currency.

When to use it

Guide: Currency exchange rate API

Run it free (25 free calls) Buy credits by card (from $1) Example result (JSON)

Try it with your own inputs

Base currency as a three-letter ISO 4217 code, e.g. USD

Uses one of your 25 free calls. Nothing is charged, and a call that fails is not counted.

Inputs

NameTypeDescription
from (required)stringBase currency as a three-letter ISO 4217 code, e.g. USD
tostringOptional comma-separated target currency codes, e.g. EUR,GBP; default is all available currencies
amountnumberOptional amount of the base currency to convert (default 1)

Request

Over HTTP, with a card key from /credits:

curl -H "Authorization: Bearer adt_…" "https://tools.funwords.eu/fx?from=USD"

Or one of your 25 free calls, no key:

curl "https://tools.funwords.eu/fx?from=USD&trial=1"

Without a key, the same URL answers 402 Payment Required with x402 and MPP terms, so an agent with a wallet pays per call in USDC (Base, Polygon, Arbitrum or Solana over x402; Base or Tempo over MPP) and retries.

Example result

{
  "from": "USD",
  "amount": 100,
  "rateDate": "2026-10-12",
  "rates": {
    "EUR": 0.89437,
    "GBP": 0.75555,
    "SEK": 10.0139
  },
  "converted": {
    "EUR": 89.437,
    "GBP": 75.555,
    "SEK": 1001.39
  },
  "source": "European Central Bank reference rates (one rate per working day, published around 16:00 CET)",
  "checkedAt": "2026-10-13T09:00:00.000Z"
}

From an AI agent (MCP)

Add the MCP server to Claude, Cursor or any MCP client. This tool is fx, and the first 25 successful calls are free:

https://tools.funwords.eu/mcp

Questions

How often are rates updated?

Daily reference rates from the source named in the result.

How do I pay?

Each successful call costs $0.01; failed calls are not charged. The first 25 calls are free. Then pay with card credits (from $1; the key goes in an Authorization header or, for clients that can only fetch a URL, as api_key= in the URL) or per call in USDC over x402 or MPP. No account is needed.

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