Every exchange rate API returns numbers for currency pairs. The real differences are how often rates update, how much history you get, whether you can change the base currency, which endpoints each plan includes and what you pay at your volume.
Which exchange rate API is best?
No single API is best for everyone. Based on each provider’s published plans:
- Free, no API key, official sources: Frankfurter – daily central-bank rates, history since 1948.
- Free plan with history, any base currency and period averages: fxapi – Free gives you 300 requests a month.
- Largest keyed free quotas: UniRate API (200 requests a day, no historical data) and CurrencyBeacon (5,000 requests a month, fixed base).
- 60-second updates at the lowest listed price: fxapi Professional and CurrencyAPI.net StartUp, both $34.99 a month.
- Lowest entry-plan cost per request: UniRate API ($9 for 25,000 requests a day) and FastForex (from $18 for 1,000,000 requests).
- Unlimited requests: Open Exchange Rates Unlimited, $97 a month.
- Bid/ask rates and WebSockets: FastForex.
- Accounting averages for IAS 21 and ASC 830: fxapi – its average endpoint is on every plan, including Free.
Exchange rate API pricing and features compared
“Cost per 100k” is the entry paid plan’s monthly price divided by its monthly request quota, multiplied by 100,000. Use it to compare plans on equal terms; it is not a quote for your exact usage. Prices exclude VAT.
| API | Free tier | Entry paid plan | Cost per 100k (entry plan) | Base currency | Fastest update | Historical data |
|---|---|---|---|---|---|---|
| fxapi | 300 req/month, daily, no credit card | $9.99/month (15,000) | $66.60 on Basic; $5.83 on Professional; $4.41 on Enterprise | Any base, every plan incl. Free | 60 s (Professional, $34.99) | Daily since 1 Jan 1999, every plan |
| Open Exchange Rates | 1,000 req/month, hourly | $12/month (10,000) | $120.00; Unlimited $97 with no request cap | USD only on Free | 5 min (Unlimited, $97); up to 1 s on VIP (on request) | All plans |
| ExchangeRate-API | 1,500 req/month, daily | $10/month (30,000) | $33.33 | – | 5 min (Business, $30) | Pro: over 30 years |
| CurrencyFreaks | 1,000 calls/month, daily | $9.99/month (15,000) | $66.60 | USD only on Free | 60 s (Professional, $99.99) | Back to 28 Nov 1984; Starter and up |
| CurrencyBeacon | 5,000 req/month, hourly | $10/month (50,000) | $20.00 | Switching from Startup ($99) | 1 min (Startup, $99); real-time on Professional ($599) | All plans |
| CurrencyAPI.net | 500 req/month, hourly, personal use only | $9.99/month (20,000) | $49.95; Professional $74.99 for 10,000,000 (≈ $0.75) | Fixed on Free | 60 s (StartUp, $34.99) | Essential and up |
| FastForex | 7-day trial, no permanent free plan | From $18/month (1,000,000) | $1.80 | – | 60 s on One; 1 s on Premium | Back to 1970 for select pairs |
| UniRate API | 200 req/day, no historical data | $9/month (25,000/day) | ≈ $1.20 (25,000/day × 30 days) | – | “Real-time” (no interval stated) | 1999–2026; Pro only |
| AllRatesToday | 10 req/min, personal and non-commercial use | €4.99/month (5,000) | €99.80 | – | 1 min on paid plans | Paid plans |
| Frankfurter | Free, no key, no quotas (rate-limited) | – (open source, self-hostable) | $0 | – | Daily | Since 1948 |
“–” means the provider’s pricing page doesn’t state it. See that provider’s comparison page or its own docs.
Extras, AI-agent support and watch-outs
| API | MCP server for AI agents | Notable extras | Watch-outs |
|---|---|---|---|
| fxapi | Hosted, all 11 endpoints as tools | Fluctuation and monthly/quarterly/yearly averages on every plan; time series up to 366 days per call and OHLC candles (Professional); JSON, CSV and XLSX output; 16 cryptocurrencies plus gold, silver, platinum and palladium; official SDKs for 6 languages; OpenAPI 3.1; EU-based (Austria) | Mid-market reference rates only: no bid/ask or trade execution. Free plan is 300 requests a month. Convert starts on Basic, time series and OHLC on Professional. |
| Open Exchange Rates | Not stated | Unlimited-request plan; time series from Enterprise ($47); VIP adds bid/ask and OHLC | Free plan is USD base and hourly |
| ExchangeRate-API | Not stated | Volume plan ($700 a year) | Free plan updates once a day |
| CurrencyFreaks | Linked from its site | IP-to-currency (Growth and up); time series and fluctuation (Professional) | 60-second updates start at $99.99 |
| CurrencyBeacon | Hosted, every plan (calls share the quota) | Large free quota; history and conversion on every plan; crypto | Base currency switching only from $99; terms prohibit redistribution without permission |
| CurrencyAPI.net | Not stated | OHLC on Professional | Free plan is personal use only |
| FastForex | Promoted on its site | Bid/ask from Extra; WebSockets on Premium + WebSockets; ~55 years of OHLC on Premium | No permanent free plan |
| UniRate API | Not stated | VAT rates and VAT number validation, IBAN validation, holiday and market calendars, commodities | History and time series on Pro only |
| AllRatesToday | Not stated | Official rates of 123 central banks and 4 tax authorities on Business (€239); XLSX on Business | Free plan is personal and non-commercial |
| Frankfurter | Yes (frankfurter.dev/mcp/) | 228 currencies from 106 central banks and official sources; open source | Daily updates only; rate-limited |
Plans and prices checked on October 28, 2026 from openexchangerates.org/signup, exchangerate-api.com, currencyfreaks.com/pricing, currencybeacon.com/pricing, currencyapi.net/pricing, fastforex.io, unirateapi.com/pricing, allratestoday.com/pricing and frankfurter.dev. Cost per 100k is calculated from the quotas those pages list. Plans change, so verify on each provider’s site before you decide. If you spot something out of date, tell us and we’ll correct it.
Best exchange rate API by use case
E-commerce and multi-currency pricing. Checkout prices usually need hourly or faster rates. fxapi updates hourly on Basic ($9.99) and every 60 seconds on Professional ($34.99); CurrencyAPI.net also offers 60 seconds at $34.99. CurrencyBeacon’s free plan updates hourly.
Accounting and IAS 21 / ASC 830 reporting. You need period averages and consistent history. fxapi’s average exchange rates API returns monthly, quarterly and yearly averages with min/max, as JSON or CSV, on every plan. If your auditor requires official central-bank rates, look at Frankfurter or AllRatesToday’s Business plan.
Fintech, payments and trading. If you need bid/ask spreads or streaming, fxapi is not the right fit: it provides mid-market rates only. FastForex offers bid/ask from its Extra plan, plus WebSockets. For OHLC candles, fxapi (Professional) and CurrencyAPI.net (Professional) both have them.
BI, analytics and backtesting. You want deep history and a range in one request. fxapi’s time series API returns up to 366 days of daily rates per call on Professional, with daily history since 1999. For data before 1999, Frankfurter (1948), FastForex (1970, select pairs) and CurrencyFreaks (1984) go further back.
AI agents and coding assistants. fxapi, CurrencyBeacon, FastForex, CurrencyFreaks and Frankfurter offer MCP servers. fxapi’s MCP server at https://api.fxapi.com/mcp exposes all 11 endpoints as tools.
Hobby projects and prototypes. Frankfurter needs no key or signup. If you need a non-USD base or history on a free plan, see what fxapi’s free exchange rate API includes.
How to choose an exchange rate API
- Update frequency. Daily rates are fine for invoices, reports and most analytics. Checkout pricing and payments usually need hourly or faster – see end-of-day vs real-time rates.
- Base currency. If your books or prices aren’t in USD, check whether the plan you’ll actually use lets you change the base. Several free plans are USD-only, so you’d compute cross rates yourself and add rounding error.
- History and time series. Backtesting and reporting need deep, consistent history and a time-series endpoint that returns a whole range in one request. One request per day for a year of data costs 365 requests.
- Accounting needs. IAS 21 and ASC 830 often call for period averages – an average exchange rates API saves you from averaging daily data yourself.
- Cost at your volume. Work out your monthly requests a year from now, then price the plan that covers them. For example, 100,000 requests a month on fxapi needs Professional: $34.99 for 600,000 requests, or $5.83 per 100k. Yearly billing on fxapi gives two months free. Full plans are on the pricing page.
- Terms of use. Check attribution and redistribution rules, caching limits and whether the free plan allows commercial use. The watch-outs column above lists the ones we found.
- Data provenance. If you must cite an official source, you may need a central-bank-based API such as Frankfurter. fxapi provides mid-market reference rates for pricing, conversion, reporting and analytics.
Each comparison page below covers free plans, pricing, history and endpoints, with an endpoint map so you can estimate the work of switching to fxapi.