{"name":"fx_rate","intro":"European Central Bank reference rates, served by [Frankfurter](https://frankfurter.dev). Mid-market rates published once a business day — right for reporting and estimates, not a retail quote. The result includes `rates_table_for_convert`, which goes straight into [`convert`](/docs/tools/convert) as `rates`.","when_to_use":["Before converting money: [`convert`](/docs/tools/convert) deliberately refuses to invent a rate.","Historical rates for a specific date, for invoices and restatements.","Not for crypto or retail card rates — the ECB publishes neither."],"network":true,"related":"[`convert`](/docs/tools/convert) does the arithmetic once you have the rates.","docs_url":"/docs/tools/fx_rate","parameters":[{"name":"base","type":"string","required":false,"doc":"The currency the rates are quoted against, ISO 4217.","default":"`USD`"},{"name":"to","type":"string \\| string[]","required":false,"doc":"One code, a list of codes, or a comma-separated string. Omitted returns every published rate.","default":null},{"name":"date","type":"string","required":false,"doc":"`YYYY-MM-DD` for a historical rate; omitted uses the latest business day.","default":null},{"name":"amount","type":"number","required":false,"doc":"Converted as well as quoted, when exactly one target currency is given.","default":null}]}