Currency & Exchange Rate API FAQ

Is there a free API for currency conversion?

Yes — several. The main free options in 2026:

• Frankfurter — 100% free, open-source, no API key, ECB reference rates for ~30 currencies, historical data back to 1999.
• fawazahmed0/currency-api — free via jsDelivr CDN, 200+ currencies including crypto, no key.
• AllRatesToday — free plan with hourly updates for 160+ currencies, API key required but no credit card.
• ExchangeRate-API — free tier with 1,500 requests/month (API key required).
• freecurrencyapi.com — free tier with 5,000 requests/month.
• Fixer.io — free tier with 100 requests/month (HTTP only on free).

If you're building a JavaScript app, the live-currency-rates npm package wraps Frankfurter, fawazahmed0, and AllRatesToday under one fluent API — you can switch with one line: setup({ provider: 'frankfurter' }).

What is a currency API?

A currency API is a REST web service that returns exchange rates between currencies, usually as JSON. Typical calls look like:

# Frankfurter (free, no key)
GET https://api.frankfurter.dev/v1/latest?from=USD&to=EUR
→ { "amount": 1, "base": "USD", "date": "2026-04-18", "rates": { "EUR": 0.84767 } }

# AllRatesToday (free plan, API key)
GET https://allratestoday.com/api/v1/rates?source=USD&target=EUR
Authorization: Bearer art_live_...
→ [{ "rate": 0.85, "source": "USD", "target": "EUR", "time": "..." }]

Currency APIs are used in e-commerce checkout (showing prices in the shopper's local currency), finance dashboards, accounting tools, travel apps, international payroll, and anywhere software needs to convert or display money across currencies.

What is a forex API?

A forex (FX) API is a currency API built for trading rather than display. It delivers:

• Tick-level bid/ask quotes with millisecond latency (not just a mid-market rate)
• Historical OHLC data for charting
• Sometimes order execution endpoints (place, modify, cancel)

Forex APIs include OANDA, MetaTrader (MT4/MT5), TraderMade, Polygon.io, and FXCM. General-purpose currency APIs like Frankfurter or ExchangeRate-API only return reference mid-market rates and are not intended for trading.

What is an FX API?

"FX API" is another name for "forex API." Some enterprise providers (banks, Stripe, Bloomberg, OCBC) use "FX API" specifically for streaming quotes and execution services supporting 100+ currency pairs. In casual developer conversation, "currency API" and "FX API" are often used interchangeably.

What is an open exchange rate?

Two meanings:

1. Generic: an exchange rate that's openly accessible through a public API or data feed — no private contract required.
2. Specific: Open Exchange Rates is the name of a commercial provider that has been publishing rates for 200+ currencies since 2011. Free tier: 1,000 requests/month (hourly updates, USD base only).

Is the Frankfurter API free?

Yes. Frankfurter is a free, open-source currency data API with no key, no signup, and no documented rate limit for normal use. It tracks ~30 currencies using European Central Bank daily reference rates and supports historical data back to 1999. Because it's ECB-based, rates update once per business day around 16:00 CET — it's great for accounting, invoicing, and general display, but not for trading.

Is an exchange rate API free?

Depends on the provider:

Is ExchangeRate-API free?

ExchangeRate-API offers a free plan of 1,500 requests/month, no credit card required. It's fine for hobby projects, prototypes, and small internal tools. The free tier is not intended for production traffic — the terms explicitly ask commercial users to upgrade.

How much does ExchangeRate-API cost?

As of 2026, ExchangeRate-API paid plans:

• Pro: $13.99/month — 30,000 requests/month, hourly updates
• Business: $29/month — 100,000 requests/month
• Volume: $49/month — 1.5M requests/month, minute-level updates
• Enterprise: custom pricing for higher volumes and SLAs

Check the ExchangeRate-API pricing page for current numbers — they change occasionally.

Does Xe have an API?

Yes. Xe Currency Data API provides real-time and historical exchange rates for 170+ currencies. It's used by Fortune 500 companies, banks, and fintechs. The API includes mid-market rates, a historical archive, and optional delivery SLAs.

Is the Xe API free?

No. Xe has no public free tier. Pricing is enterprise-only and typically starts around $799/month depending on request volume and feature mix. If you need free access, use Frankfurter, AllRatesToday's free plan, ExchangeRate-API's free tier, or freecurrencyapi.com.

Is the Google Currency Converter API free?

There is no official public Google Currency API. What exists:

• The GOOGLEFINANCE function in Google Sheets (free, ~20-minute delay)
• Unofficial wrappers like currency-api.appspot.com (community-hosted, no SLA)

For production code, don't depend on Google for currency rates — use a supported provider like AllRatesToday, Frankfurter, or ExchangeRate-API.

Is Fixer.io reliable?

Yes, within its bounds. Fixer.io is owned by apilayer and has been operating since 2015. Paid plans have uptime guarantees and are generally considered reliable. Limitations on the free tier are heavy: 100 requests/month, HTTP only (no HTTPS), and EUR is the only allowed base currency — most production users end up on Basic ($14.99/month) or Professional ($59.99/month). If Fixer's free-tier restrictions are a problem, AllRatesToday's free plan lifts the base-currency restriction and supports HTTPS out of the box.

Is the MT5 API free?

No. MetaTrader 5 Manager and Gateway APIs are not free — they require a licensed MT5 server and a paid integration agreement with MetaQuotes. Brokers may offer trial access to demo accounts. If you only need exchange rates (not trade execution), a plain currency API like Frankfurter or AllRatesToday is drastically simpler and cheaper.

How do you make a currency converter in Python with an API?

Minimal working example using Frankfurter (no key required):

import requests

def convert(amount, src, dst):
    r = requests.get("https://api.frankfurter.dev/v1/latest",
                     params={"from": src, "to": dst})
    r.raise_for_status()
    rate = r.json()["rates"][dst]
    return amount * rate, rate

amount, rate = convert(100, "USD", "EUR")
print(f"100 USD = {amount:.2f} EUR  (rate {rate})")

Add error handling for connection failures and unknown currency codes, cache results for 30–60 minutes to stay polite with the free API, and you're done. If you need higher-frequency updates, swap the URL to https://allratestoday.com/api/v1/rates with an Authorization: Bearer header — same shape, just returns rates faster.

What is the formula to calculate an exchange rate?

The exchange rate is the ratio of two currency amounts:

rate = target_amount / source_amount

If 100 USD buys 85 EUR, the USD→EUR rate is 85 / 100 = 0.85. To convert any amount, multiply by the rate:

250 USD × 0.85 = 212.50 EUR

The inverse (EUR→USD) is 1 / 0.85 ≈ 1.176. Note that real-world rates include a spread — the "buy" and "sell" rates differ slightly, and that difference is the provider's margin.

What is the GOOGLEFINANCE function for exchange rates?

In Google Sheets, use:

=GOOGLEFINANCE("CURRENCY:USDEUR")

Replace USDEUR with any two concatenated ISO 4217 codes (e.g. GBPJPY, AUDCAD). For historical rates, add a date:

=GOOGLEFINANCE("CURRENCY:USDEUR", "price", DATE(2024,1,1))

Rates are delayed by ~20 minutes and cover most major pairs. Fine for spreadsheets; don't use it for production apps.

Which is the best currency converter?

Depends on the use case:

• Sending money abroad: Wise — real mid-market rate, no hidden markup.
• Quick lookup on web/mobile: Google search (100 usd to eur) or XE.com.
• Embedding in software: Frankfurter (free), AllRatesToday (free plan, 160+ currencies), or ExchangeRate-API (free tier). The live-currency-rates npm package gives you them under one fluent API.
• Enterprise / trading: Xe, OANDA, or Bloomberg.

What is the best currency converter app to use?

Most-recommended consumer apps in 2026:

• Wise — best mid-market rate + actual money transfer.
• XE Currency — clean UI, offline mode for travel.
• Revolut — multi-currency account with in-app conversion.
• Currency Converter Plus — simple free converter (ad-supported).

Where should you convert currency for the best exchange rate?

You get closest to the true mid-market rate with online-first providers: Wise, Revolut, Currencies Direct, or OFX. Traditional banks and airport kiosks typically mark up the rate by 2–5% on top of a fee. Travel-friendly credit cards (no foreign transaction fee) are good for purchases abroad; avoid "Dynamic Currency Conversion" at the point of sale — always pay in the local currency.

Rule of thumb: check the mid-market rate on Google, this converter, or AllRatesToday, then compare what you're offered. Any gap is the provider's margin.