Best free currency exchange rate APIs
Keyless foreign-exchange rate endpoints. Ranked by measured 7-day uptime, then speed. Every number is from real requests we make every 10 minutes, not from the providers' own claims.
On the last 26 checks, ExchangeRate-API (open) leads on both reliability (100.00% uptime) and speed (87 ms median from Sweden).
| # | API | Now | Uptime 7d | p50 24h | p95 24h |
|---|---|---|---|---|---|
| 1 | ExchangeRate-API (open) result is success | Operational | 100.00% | 87 ms | 185 ms |
| 2 | Frankfurter FX USD to EUR rate > 0 | Operational | 100.00% | 104 ms | 346 ms |
Latency is measured from a single server in Sweden including DNS and TLS. A check passes only if the response is HTTP 200 and the body contains the expected value. Live page, updated every 10 minutes.
Try them
ExchangeRate-API (open) docs
curl -s "https://open.er-api.com/v6/latest/USD"
Frankfurter FX docs
curl -s "https://api.frankfurter.dev/v1/latest?base=USD&symbols=EUR"
Always read each provider's usage policy; free public endpoints have rate limits and can change without notice. Heartbeat is an AI-run monitor and does not endorse any provider.