Exchange Rate

Get the current exchange rate between two currencies from the European Central Bank, with the inverse rate and the date.

Pay by wallet (x402) exchange-rate

Example

Input

{
  "to": "EUR",
  "from": "USD"
}

Answer

{
  "to": "EUR",
  "date": "2026-03-06",
  "from": "USD",
  "rate": 0.864977,
  "inverse_rate": 1.1561
}

Inputs

Field	Type	Required	What it is
`to`	string	Yes	Target currency (ISO 4217, e.g. EUR)
`from`	string	Yes	Source currency (ISO 4217, e.g. USD)

Output fields

How reliably each field appears in a successful answer.

Field	Type	Appears
`to`	string	Always (present in every successful answer)
`date`	string	Always (present in every successful answer)
`from`	string	Always (present in every successful answer)
`rate`	number	Always (present in every successful answer)
`inverse_rate`	number	Always (present in every successful answer)

How to call it

The same tool through each route. MCP clients reach it through Strale’s server at https://api.strale.io/mcp; the call below is what the agent sends.

# Needs an API key. max_price_cents caps what this call may cost.
curl -X POST https://api.strale.io/v1/do \
  -H "Authorization: Bearer $STRALE_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{
    "capability_slug": "exchange-rate",
    "inputs": {
      "to": "EUR",
      "from": "USD"
    },
    "max_price_cents": 2
  }'

{
  "tool": "strale_execute",
  "arguments": {
    "slug": "exchange-rate",
    "inputs": {
      "to": "EUR",
      "from": "USD"
    },
    "max_price_cents": 2
  }
}

import { Strale } from "straleio";

const strale = new Strale({ apiKey: process.env.STRALE_API_KEY! });
const result = await strale.do({
  capability_slug: "exchange-rate",
  inputs: {
    "to": "EUR",
    "from": "USD"
  },
  max_price_cents: 2,
});

import os
from straleio import Strale, DoRequest

strale = Strale(api_key=os.environ["STRALE_API_KEY"])
result = strale.do(DoRequest(
    capability_slug="exchange-rate",
    inputs={
        "to": "EUR",
        "from": "USD",
    },
    max_price_cents=2,
))

# No account. The first request answers 402 with the price in USDC;
# an x402 client pays it from your wallet and repeats the request.
curl -i 'https://api.strale.io/x402/v2/exchange-rate?to=EUR&from=USD'

Limitations

Rates can be stale on weekends and holidays
Rates updated every hour during market hours, may be stale during weekends and holidays
What to do instead: For weekend transactions, use the Friday close rate and flag the amount for reconciliation on Monday
Bank conversion rates can differ by 0.5–3%
Mid-market rates — actual bank conversion rates will differ by 0.5-3% depending on provider
What to do instead: Apply your bank's typical spread as a margin buffer (e.g., ±1.5%) when displaying converted amounts to users

Bundled checks that include it

SEPA Payment Readiness €0.30

Related tools

Currency Converter €0.02
Stock Quote €0.05