← Currency converter

Convert currencies in Node.js

Convert between about 30 currencies using the European Central Bank's daily reference rates. Here is the whole call in Node.js, with the output it produced when we ran it.

Before you start

• An API key. Create a free account; it comes with free tokens every month. Put the key in an environment variable so it stays out of your code: export BLOODWEB_KEY=your_key
• Node.js 18 or later. Nothing to install: fetch, FormData and Blob are built in. Save the file with the .mjs ending so await works at the top level.

The code

Save it as currency-convert.mjs and run node currency-convert.mjs.

// Node.js 18 or later: fetch, FormData and Blob are built in.

const url = new URL("https://bloodweb.net/api/v1/currency-convert");
url.search = new URLSearchParams({ amount: "100", from: "AUD", to: "USD,INR" });

const res = await fetch(url, {
  headers: { Authorization: `Bearer ${process.env.BLOODWEB_KEY}` },
});
if (!res.ok) throw new Error(`${res.status}: ${(await res.json()).error.message}`);
console.log(await res.json());

What you get

Tested 19 October 2026: this exact code ran against our test copy of the API, which runs the same service code as bloodweb.net, and produced this.

The API answers with JSON:

{
    "amount": 100,
    "from": "AUD",
    "date": "2026-10-16",
    "rates": {
        "USD": 0.695875,
        "INR": 66.0837
    },
    "results": {
        "USD": 69.5875,
        "INR": 6608.373
    },
    "source": "European Central Bank reference rates, via Frankfurter",
    "stale": false
}

Change the call

Every option the Currency converter takes. Add or change them the same way as the ones in the code.

• amount: The amount to convert.
• from required: Three-letter currency code, such as AUD.
• to: One or more codes, comma separated. Leave out for every currency.
• date: A past date as YYYY-MM-DD, for that day's rates (back to 4 January 1999). Weekends and holidays use the last working day before. Leave out for the latest.

If it fails

A failed call is not charged. The answer is JSON with an error object; the code above prints its message. The usual ones:

• 401 missing_key or invalid_key: BLOODWEB_KEY is not set in the shell that runs the code, or the key was revoked.
• 400 bad_param: a value is wrong or missing. The message names the parameter.
• 402 insufficient_tokens: the balance does not cover the call. Top up in the dashboard.
• 429 rate_limited: too many calls at once. Wait the seconds in the Retry-After header and send it again.

Every code and its fix is in the docs.

Next

• The Currency converter page: every option, the limits, and Try it now in your browser.
• Getting started: keys, errors and rate limits for all the services.