7 Best Currency Exchange Rate APIs in 2026 (Free Tiers Compared)

Strongwell Currency/FX API — Fastest, Freshest Data

Strongwell's Currency/FX API tops our ranking for developers who need the freshest data at the best price. Exchange rates update every 15 minutes — on all tiers, including free. That's 4x fresher than the next-best option's free tier. Running on Cloudflare's edge network, response times are consistently under 200ms worldwide.

The API supports 170+ currencies with any base currency on the free tier (most competitors lock you to EUR or USD). The pay-per-request model ($0.002/request) means you only pay for what you use — no monthly minimums or unused plan capacity.

For an app making 50,000 requests/month, that's $100 — compared to Open Exchange Rates' $49/month (150K limit) or Fixer's $29.99/month. The pricing is competitive at moderate volumes and advantageous for variable-volume applications.

Try it: currency-fx-api.strongwell.workers.dev

Open Exchange Rates — Best for Historical Data

Open Exchange Rates has been operating since 2012, making it one of the most mature currency APIs available. Their standout feature is comprehensive historical data going back to 1999, essential for financial applications, reporting, and analytics.

The free tier (1,000 requests/month, USD base only) is adequate for development. Paid plans start at $12/month for any base currency, time-series data, and hourly updates. Documentation is excellent with official libraries for most languages.

ExchangeRate-API — Best Budget Monthly Plan

ExchangeRate-API strikes a good balance between affordability and reliability. Their 1,500/month free tier is generous, and paid plans start at just $4.99/month — the lowest monthly subscription on this list. The API is simple, well-documented, and reliable.

The main limitation is daily-only updates on the free tier. For applications where rates can be a day old (travel planning, informational displays), this is fine. For e-commerce or financial applications needing fresher data, look at options with more frequent updates.

CurrencyAPI.com — Modern and Well-Designed

CurrencyAPI.com offers a modern API with clean documentation and 170+ currencies. Their free tier (300 requests/month) is modest, but paid plans ($9.99/month) unlock minute-by-minute updates and historical data. A solid middle-ground option with no major weaknesses.

Fixer.io — Legacy Standard

Fixer.io was the original go-to currency API, but since the Apilayer acquisition, its free tier has become the most restrictive on this list (100 requests/month, EUR base only, HTTP only). It remains widely used and reliable, but new projects should compare alternatives — several offer better value.

See our detailed Fixer.io alternatives comparison for more.

Frankfurter — Best Free Open-Source

Frankfurter is completely free with no API key required — backed by ECB data, updated daily. It supports about 33 currencies (major world currencies). For hobby projects, learning, and prototyping, you can't beat the price. No SLA and limited currency coverage make it unsuitable for production applications requiring reliability or exotic currencies.

FreeCurrencyAPI — Highest Free Volume

FreeCurrencyAPI offers 5,000 free requests per month — the most generous count on this list. The catch: only 32 currencies supported. If your application only needs major currencies (USD, EUR, GBP, JPY, etc.), this is an excellent free option. For broader currency coverage, look elsewhere.