Building a travel app, e-commerce store, or financial dashboard? You need reliable exchange rates. But popular APIs often come with strict limits, complex pricing, or mandatory sign-ups.
In 2025, developers want simplicity.
Here is our curated list of the best free currency exchange APIs, starting with the easiest one to use.
1. FastTools Currency API (Powered by Frankfurter)
Best for: Developers who want to start coding right now.
Our own Currency API is built on the robust, open-source Frankfurter engine. We believe essential data should be accessible.
- No API Key Required: Just fetch the URL.
- Completely Free: No "freemium" traps.
- Real-Time: Updates every business day from the European Central Bank.
- Historical Data: Track rates back to 1999.
Example Request:
bash
GET https://api.frankfurter.dev/v1/latest?from=USD&to=EUR,GBP
2. ExchangeRate-API
Best for: High availability needs.
A solid "freemium" option. The free tier is generous (1,500 requests/month) and supports 160+ currencies. It requires an email sign-up to easier management.
3. Open Exchange Rates
Best for: Enterprise-grade data.
One of the oldest players. The free plan is limited but provides hourly updates. It's an industry standard for a reason, but can be overkill for small projects.
4. Fixer.io
Best for: European market data.
Known for its high accuracy with EU data sources. The free plan is limited to 1,000 requests/month and base currency is restricted to EUR on the free tier, which can be a blocker for some.
5. CurrencyFreaks
Best for: Crypto support.
If you need fiat AND crypto rates in one place, this is a distinct choice. It supports hundreds of cryptocurrencies alongside traditional money.
Why "No Key" Matters for Side Projects
When you're hacking on a weekend project or learning a new framework, stopping to register for an account, verify email, and copy-paste keys kills momentum.
APIs like ours allow you to:
- Open your terminal.
curlthe endpoint.- See data immediately.
Conclusion
For most developers in 2025, the FastTools Currency API offers the best balance of ease, specific features, and cost (free!).
Stop worrying about rate limits and start building.