ustreasury-exchange-rate — U.S. Department of the Treasury exchange rates for Node.js

Official U.S. Department of the Treasury (United States) exchange rates in Node.js and TypeScript with the ustreasury-exchange-rate npm package: latest published table, any historical date, daily series. Zero dependencies, types included.

U.S. Department of the Treasury · United States · home currency USD · published every business day

Installation

npm install ustreasury-exchange-rate
# or
yarn add ustreasury-exchange-rate
pnpm add ustreasury-exchange-rate

The same code is also published under the org scope as @allratestoday/ustreasury-exchange-rate — identical versions, pick whichever naming fits your dependency policy. Zero runtime dependencies; ESM and CommonJS builds; TypeScript definitions included.

Quick start

You need a free API key from allratestoday.com/register — no credit card, and the latest U.S. Department of the Treasury table is on every plan.

import { getRate } from 'ustreasury-exchange-rate';

const pair = await getRate('USD', 'EUR', { apiKey: 'art_live_...' });
console.log(pair.rate, pair.rate_date);
// the official U.S. Department of the Treasury rate, on the tax authority's own publication date

API reference

Four functions, all returning promises. Every function takes an options object with your apiKey; the package throws before making a request if it is missing.

getRate(source, target, options)

Free plan and up. One pair from the latest published table. Pairs U.S. Department of the Treasury does not print directly are resolved from its own table and flagged (see published vs derived).

const pair = await getRate('USD', 'EUR', { apiKey: 'art_live_...' });

// →
{
  bank: 'ustreasury',
  name: 'U.S. Department of the Treasury',
  rate_date: '2026-08-21',   // U.S. Department of the Treasury's own publication date
  source: 'USD',
  target: 'EUR',
  rate: 0.854774,
  rate_type: 'reference',
  derived: false,
  method: 'published',       // 'published' | 'inverse' | 'cross'
  disclaimer: '…'
}

getLatestRates(options)

Free plan and up. The complete table for the latest publication date — one call, every currency U.S. Department of the Treasury prints.

import { getLatestRates } from 'ustreasury-exchange-rate';

const table = await getLatestRates({ apiKey: 'art_live_...' });
console.log(table.rate_date, table.rates.length);

// →
{
  bank: 'ustreasury',
  name: 'U.S. Department of the Treasury',
  rate_date: '2026-08-21',
  rates: [
    { base: 'USD', quote: 'USD', type: 'reference', value: 1.1699 },
    // … the rest of the published table
  ],
  disclaimer: '…'
}

getRatesForDate(date, options)

Paid plans. The official table for any past date. Weekends and holidays return the most recent published table, flagged via published_on_requested_date — exactly the in-force rate a filing or invoice needs. Pass source/target in the options to narrow to one pair.

import { getRatesForDate } from 'ustreasury-exchange-rate';

const day = await getRatesForDate('2026-06-30', { apiKey: 'art_live_...' });
const one = await getRatesForDate('2026-06-30', { apiKey: 'art_live_...', source: 'USD', target: 'EUR' });

// →
{
  bank: 'ustreasury',
  requested_date: '2026-06-30',
  rate_date: '2026-06-30',              // the date actually published
  published_on_requested_date: true,    // false when a weekend/holiday fell back
  rates: [ /* the full table for that date */ ],
  disclaimer: '…'
}

getHistory(query, options)

Paid plans. One resolved rate per publication date across a range — for charts, revaluation runs or audit workpapers. Pass { symbol: 'USD' } instead of source/target to get the raw published rows for one currency.

import { getHistory } from 'ustreasury-exchange-rate';

const series = await getHistory(
  { source: 'USD', target: 'EUR', from: '2026-01-01', to: '2026-08-21' },
  { apiKey: 'art_live_...' }
);

// →
{
  bank: 'ustreasury',
  source: 'USD',
  target: 'EUR',
  from: '2026-01-01',
  to: '2026-08-21',
  count: 152,
  rates: [
    { date: '2026-08-21', rate: 0.854774, rate_type: 'reference', derived: false, method: 'published' },
    // … one entry per publication date
  ],
  disclaimer: '…'
}

Published vs derived rates

If U.S. Department of the Treasury does not print a pair directly, the API resolves it from the tax authority's own table and says so — official and computed values are never mixed:

Error handling

Errors are thrown as Error with status (HTTP code) and body (the API's JSON error) attached:

try {
  const pair = await getRate('USD', 'XXX', { apiKey: 'art_live_...' });
} catch (err) {
  console.log(err.message); // human-readable reason
  console.log(err.status);  // e.g. 404
}

TypeScript and CommonJS

Full definitions ship with the package — no @types install:

import type { LatestRates, PairRate, DatedRates, RateEntry, HistoryQuery, RequestOptions } from 'ustreasury-exchange-rate';

CommonJS works too:

const { getRate } = require('ustreasury-exchange-rate');

getRate('USD', 'EUR', { apiKey: 'art_live_...' }).then((pair) => console.log(pair.rate));

Quota tips

• U.S. Department of the Treasury publishes every business day — cache the table locally and a small monthly quota goes a long way.
• Every request counts toward your AllRatesToday quota, shared across all endpoints on your key.
• Prefer getLatestRates (one call, whole table) over many getRate calls when you need several pairs.

Under the hood

The package is a thin, dependency-free wrapper over the REST endpoints documented on the U.S. Department of the Treasury rates page:

GET /api/v1/central-bank/ustreasury/latest?source=USD&target=EUR
GET /api/v1/central-bank/ustreasury/latest
GET /api/v1/central-bank/ustreasury/2026-06-30
GET /api/v1/central-bank/ustreasury/history?source=USD&target=EUR&from=2026-01-01&to=2026-08-21

Same data is available as CSV/XLSX downloads on the no-code download page, and to AI agents via the MCP server.

FAQ

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